sdl_gfx: refactor *_CONF_OPT assignment with cpu-feature options

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/sdl_gfx/sdl_gfx.mk

@@ -11,13 +11,7 @@ SDL_GFX_DEPENDENCIES = sdl
 SDL_GFX_CONF_OPT = \
 	--with-sdl-prefix=$(STAGING_DIR)/usr \
 	--disable-sdltest \
-	--enable-static
-
-# enable mmx for newer x86's
-ifeq ($(BR2_i386)$(BR2_x86_i386)$(BR2_x86_i486)$(BR2_x86_i586)$(BR2_x86_pentiumpro)$(BR2_x86_geode),y)
-SDL_GFX_CONF_OPT += --enable-mmx
-else
-SDL_GFX_CONF_OPT += --disable-mmx
-endif
+	--enable-static \
+	$(if $(BR2_X86_CPU_HAS_MMX),--enable-mmx,--disable-mmx)
 
 $(eval $(call AUTOTARGETS))