package/qt5base: provide "qt.conf" to make "qmake" relocatable

The file "qt.conf" can be used to override the hard-coded paths that are
compiled into the Qt library. We need it to make "qmake" relocatable.

CC: Julien Corjon <corjon.j@ecagroup.com>
CC: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
[Thomas:
 - use | instead of \ as sed separator, suggested by Arnout.
 - fix indentation, suggested by Arnout.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/qt5/qt5base/qt.conf.in

@@ -0,0 +1,6 @@
+[Paths]
+Prefix=@@HOST_DIR@@/usr
+Sysroot=@@STAGING_DIR@@
+Headers=/usr/include/qt5
+Plugins=/usr/lib/qt/plugins
+Examples=/usr/lib/qt/examples

package/qt5/qt5base/qt5base.mk

@@ -258,9 +258,17 @@ define QT5BASE_BUILD_CMDS
 	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D)
 endef
 
+# The file "qt.conf" can be used to override the hard-coded paths that are
+# compiled into the Qt library. We need it to make "qmake" relocatable.
+define QT5BASE_INSTALL_QT_CONF
+	sed -e "s|@@HOST_DIR@@|$(HOST_DIR)|" -e "s|@@STAGING_DIR@@|$(STAGING_DIR)|" \
+		$(QT5BASE_PKGDIR)/qt.conf.in > $(HOST_DIR)/usr/bin/qt.conf
+endef
+
 define QT5BASE_INSTALL_STAGING_CMDS
 	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) install
 	$(QT5_LA_PRL_FILES_FIXUP)
+	$(QT5BASE_INSTALL_QT_CONF)
 endef
 
 define QT5BASE_INSTALL_TARGET_LIBS