package/qwt: prepare package to support other versions of Qt

Rework the selection of Qt options in the qwt package to make it
easier to support other versions of Qt than just Qt4. Instead of
depending on Qt options, we select the ones we need, and simply have a
global "depends on BR2_PACKAGE_QT". This also allows to remove a
comment that becomes useless.

Signed-off-by: David Picard <davepiq@yahoo.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/qwt/Config.in

@@ -1,7 +1,7 @@
 config BR2_PACKAGE_QWT
 	bool "qwt"
 	depends on BR2_PACKAGE_QT
-	depends on BR2_PACKAGE_QT_GUI_MODULE
+	select BR2_PACKAGE_QT_GUI_MODULE if BR2_PACKAGE_QT
 	help
 	  Qwt is a graphics extension to the Qt GUI application
 	  framework. It provides a 2D plotting widget and more.
@@ -12,7 +12,7 @@ if BR2_PACKAGE_QWT
 
 config BR2_PACKAGE_QWT_SVG
 	bool "SVG support"
-	select BR2_PACKAGE_QT_SVG
+	select BR2_PACKAGE_QT_SVG if BR2_PACKAGE_QT
 
 config BR2_PACKAGE_QWT_MATHML
 	bool "MathML support"
@@ -21,10 +21,6 @@ config BR2_PACKAGE_QWT_OPENGL
 	bool "OpenGL support"
 	depends on BR2_PACKAGE_HAS_LIBGLES
 	depends on BR2_PACKAGE_HAS_LIBEGL
-	select BR2_PACKAGE_QT_OPENGL_ES
+	select BR2_PACKAGE_QT_OPENGL_ES if BR2_PACKAGE_QT
 
 endif
-
-comment "qwt depends on QT gui module"
-	depends on BR2_PACKAGE_QT
-	depends on !BR2_PACKAGE_QT_GUI_MODULE

package/qwt/qwt.mk

@@ -8,7 +8,10 @@ QWT_VERSION = 6.1.2
 QWT_SOURCE = qwt-$(QWT_VERSION).tar.bz2
 QWT_SITE = http://downloads.sourceforge.net/project/qwt/qwt/$(QWT_VERSION)
 QWT_INSTALL_STAGING = YES
+ifeq ($(BR2_PACKAGE_QT),y)
 QWT_DEPENDENCIES = qt
+QWT_QMAKE = $(QT_QMAKE)
+endif
 
 QWT_LICENSE = LGPLv2.1 with exceptions
 QWT_LICENSE_FILES = COPYING
@@ -37,7 +40,7 @@ endif
 
 define QWT_CONFIGURE_CMDS
 	$(SED) $(QWT_CONFIG) $(@D)/qwtconfig.pri
-	(cd $(@D); $(TARGET_MAKE_ENV) $(QT_QMAKE))
+	(cd $(@D); $(TARGET_MAKE_ENV) $(QWT_QMAKE))
 endef
 
 define QWT_BUILD_CMDS