qt5base: add Config.in option to pass custom Qt5 options

To reduce the qt5base binary size, we can disable unnecessary features.
Instead of trying to map every qt5base option to buildroot, create a
single config that we can pass any option too. Then append those to the
ones generated by buildroot.

Signed-off-by: Brandon Maier <brandon.maier@rockwellcollins.com>
Signed-off-by: Bryce Ferguson <bryce.ferguson@rockwellcollins.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/qt5/qt5base/Config.in

@@ -16,6 +16,17 @@ config BR2_PACKAGE_QT5BASE
 
 if BR2_PACKAGE_QT5BASE
 
+config BR2_PACKAGE_QT5BASE_CUSTOM_CONF_OPTS
+	string "Custom configuration options"
+	help
+	  Define custom qt5 configuration options which can be used to
+	  enable or disable options not managed by buildroot. These
+	  options are appended to the ones generated by buildroot and
+	  passed to qt5base during configuration.
+
+	  E.g. to remove the Windows Vista style option, add the option
+	  -no-feature-style_windowsvista.
+
 config BR2_PACKAGE_QT5BASE_LICENSE_APPROVED
 	bool "Approve free license"
 	help

package/qt5/qt5base/qt5base.mk

@@ -27,6 +27,8 @@ QT5BASE_CONFIGURE_OPTS += \
 	-no-pch \
 	-shared
 
+QT5BASE_CONFIGURE_OPTS += $(call qstrip,$(BR2_PACKAGE_QT5BASE_CUSTOM_CONF_OPTS))
+
 # Uses libgbm from mesa3d
 ifeq ($(BR2_PACKAGE_MESA3D_OPENGL_EGL),y)
 QT5BASE_CONFIGURE_OPTS += -kms -gbm