package/qt5/qt5base: harfbuzz support needs gcc >= 4.8

Due to the harfbuzz bump to version 2.5.2 we need gcc >= 4.8.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/qt5/qt5base/Config.in

@@ -236,7 +236,9 @@ config BR2_PACKAGE_QT5BASE_FONTCONFIG
 
 config BR2_PACKAGE_QT5BASE_HARFBUZZ
 	bool "harfbuzz support"
-	select BR2_PACKAGE_HARFBUZZ if BR2_TOOLCHAIN_HAS_SYNC_4
+	select BR2_PACKAGE_HARFBUZZ if \
+		BR2_TOOLCHAIN_HAS_SYNC_4 && \
+		BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
 	help
 	  This option enables HarfBuzz support (either system harfbuzz
 	  if the toolchain supports __sync for 4 bytes, or the qt