qt: add patch to fix build on non-x86 platforms

This commit adds a patch to Qt that adjusts its build system to
properly support building on non-x86 platforms. The problem was due to
the PLATFORM and XPLATFORM variables having the same value when
building on a ppc64le system targetting an uncommon architecture
(Xtensa or ARC for example). We fix this problem by making sure
PLATFORM and XPLATFORM will always be different.

Fixes the following build failures occuring on gcc112 (a ppc64le
autobuilder machine):

  http://autobuild.buildroot.net/results/527747a2fbb31195bb6fdb37cfdaa624e69b7d68/
  (qt on xtensa)

  http://autobuild.buildroot.net/results/7db1265f6f34be3a498881564292517a8fc0e44e/
  (qt on ARC)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/qt/0015-configure-fix-build-on-non-x86-platforms.patch

@@ -0,0 +1,146 @@
+From 02e9698c96ca78342b82fa7239e93bab4aa45db2 Mon Sep 17 00:00:00 2001
+From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+Date: Fri, 17 Nov 2017 22:20:06 +0100
+Subject: [PATCH] configure: fix build on non-x86 platforms
+
+When building for an uncommon platform on a ppc64le machine, Qt build
+fails because it builds qmake with the target compiler instead of
+using the host compiler. This is due to the fact that Qt configure
+script believes that both the host and target platforms are "powerpc",
+even though the target really is Xtensa or ARC for example.
+
+Qt's configure script defines a variable called PLATFORM that points to
+the mkspecs describing the host machine. For x86, its value is
+qws/linux-x86-g++ and for x86-64, its value is
+qws/linux-x86_64-g++. For any other host architecture, its value is
+qws/linux-generic-g++.
+
+In parallel to this, Qt's configure script defines a variable called
+XPLATFORM that points to the mkspecs describing the target machine. It
+points to qws/linux-${CFG_EMBEDDED}-g++, where CFG_EMBEDDED is
+simply "generic" for most uncommon architectures.
+
+Therefore, when we're building for an uncommon architecture, on a
+ppc64le machine, we have:
+
+  PLATFORM = qws/linux-generic-g++
+  XPLATFORM = qws/linux-generic-g++
+
+i.e, both values are equal. Due to this, the following condition is
+false:
+
+if [ "$PLATFORM" != "$XPLATFORM" -a "$CFG_EMBEDDED" != "no" ]; then
+
+which causes Qt's configure script to fallback to:
+
+elif [ "$PLATFORM_MAC" = "yes" ] || [ -z "$CFG_ARCH" ]; then
+    CFG_ARCH=$CFG_HOST_ARCH
+fi
+
+because CFG_ARCH is not defined, and therefore gets defined to
+CFG_HOST_ARCH. So we have CFG_ARCH == CFG_HOST_ARCH, and Qt believes
+we're doing a native build.
+
+Therefore, we need to ensure that PLATFORM and XPLATFORM always have a
+different value. To achieve this, we create a
+qws/linux-host-generic-g++ mkspecs, which is always used as
+PLATFORM. It is identical to qws/linux-x86-g++. Compared to
+qws/linux-x86_64-g++, the only difference is that we're not passing
+the -m64 flag, but that isn't needed when building host tools.
+
+Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+---
+ configure                                          |  8 +----
+ mkspecs/qws/linux-host-generic-g++/qmake.conf      | 10 ++++++
+ mkspecs/qws/linux-host-generic-g++/qplatformdefs.h | 42 ++++++++++++++++++++++
+ 3 files changed, 53 insertions(+), 7 deletions(-)
+ create mode 100644 mkspecs/qws/linux-host-generic-g++/qmake.conf
+ create mode 100644 mkspecs/qws/linux-host-generic-g++/qplatformdefs.h
+
+diff --git a/configure b/configure
+index 10ad7ca0b0..d25f90be1e 100755
+--- a/configure
++++ b/configure
+@@ -2806,14 +2806,8 @@ if [ "$CFG_EMBEDDED" != "no" ]; then
+     Linux:*)
+         if [ -z "$PLATFORM" ]; then
+             case "$UNAME_MACHINE" in
+-            *86)
+-                PLATFORM=qws/linux-x86-g++
+-                ;;
+-            *86_64)
+-                PLATFORM=qws/linux-x86_64-g++
+-                ;;
+             *)
+-                PLATFORM=qws/linux-generic-g++
++                PLATFORM=qws/linux-host-generic-g++
+                 ;;
+             esac
+         fi
+diff --git a/mkspecs/qws/linux-host-generic-g++/qmake.conf b/mkspecs/qws/linux-host-generic-g++/qmake.conf
+new file mode 100644
+index 0000000000..55011ec52b
+--- /dev/null
++++ b/mkspecs/qws/linux-host-generic-g++/qmake.conf
+@@ -0,0 +1,10 @@
++#
++# qmake configuration for building with linux-g++
++#
++
++include(../../common/linux.conf)
++include(../../common/gcc-base-unix.conf)
++include(../../common/g++-unix.conf)
++include(../../common/qws.conf)
++
++load(qt_config)
+diff --git a/mkspecs/qws/linux-host-generic-g++/qplatformdefs.h b/mkspecs/qws/linux-host-generic-g++/qplatformdefs.h
+new file mode 100644
+index 0000000000..a654aa78a2
+--- /dev/null
++++ b/mkspecs/qws/linux-host-generic-g++/qplatformdefs.h
+@@ -0,0 +1,42 @@
++/****************************************************************************
++**
++** Copyright (C) 2015 The Qt Company Ltd.
++** Contact: http://www.qt.io/licensing/
++**
++** This file is part of the qmake spec of the Qt Toolkit.
++**
++** $QT_BEGIN_LICENSE:LGPL$
++** Commercial License Usage
++** Licensees holding valid commercial Qt licenses may use this file in
++** accordance with the commercial license agreement provided with the
++** Software or, alternatively, in accordance with the terms contained in
++** a written agreement between you and The Qt Company. For licensing terms
++** and conditions see http://www.qt.io/terms-conditions. For further
++** information use the contact form at http://www.qt.io/contact-us.
++**
++** GNU Lesser General Public License Usage
++** Alternatively, this file may be used under the terms of the GNU Lesser
++** General Public License version 2.1 or version 3 as published by the Free
++** Software Foundation and appearing in the file LICENSE.LGPLv21 and
++** LICENSE.LGPLv3 included in the packaging of this file. Please review the
++** following information to ensure the GNU Lesser General Public License
++** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
++** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
++**
++** As a special exception, The Qt Company gives you certain additional
++** rights. These rights are described in The Qt Company LGPL Exception
++** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
++**
++** GNU General Public License Usage
++** Alternatively, this file may be used under the terms of the GNU
++** General Public License version 3.0 as published by the Free Software
++** Foundation and appearing in the file LICENSE.GPL included in the
++** packaging of this file.  Please review the following information to
++** ensure the GNU General Public License version 3.0 requirements will be
++** met: http://www.gnu.org/copyleft/gpl.html.
++**
++** $QT_END_LICENSE$
++**
++****************************************************************************/
++
++#include "../../linux-g++/qplatformdefs.h"
+-- 
+2.13.6
+