package/sdl2: kmsdrm needs GBM

kmsdrm needs GBM (and so mesa3d) since its addition in version 2.0.6:
https://github.com/libsdl-org/SDL/commit/56363ebf6124b345e1cfbd14fb6c0e654837910c

If libgbm is not found, kmsdrm will be silently disabled

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit 5bb4e281c0c9fdd867eb7471f4e1ae82028d596d)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/sdl2/Config.in

@@ -32,10 +32,15 @@ comment "X11 video driver needs X.org"
 config BR2_PACKAGE_SDL2_KMSDRM
 	bool "KMS/DRM video driver"
 	depends on BR2_PACKAGE_LIBDRM
+	# requires libgbm from mesa3d
+	depends on BR2_PACKAGE_MESA3D_OPENGL_EGL
 
 comment "KMS/DRM video driver needs libdrm"
 	depends on !BR2_PACKAGE_LIBDRM
 
+comment "KMS/DRM video driver needs an OpenGL EGL backend provided by mesa3d"
+	depends on !BR2_PACKAGE_MESA3D_OPENGL_EGL
+
 config BR2_PACKAGE_SDL2_OPENGL
 	bool "OpenGL (GLX)"
 	depends on BR2_PACKAGE_HAS_LIBGL

package/sdl2/sdl2.mk

@@ -150,7 +150,7 @@ SDL2_CONF_OPTS += --disable-alsa
 endif
 
 ifeq ($(BR2_PACKAGE_SDL2_KMSDRM),y)
-SDL2_DEPENDENCIES += libdrm
+SDL2_DEPENDENCIES += libdrm mesa3d
 SDL2_CONF_OPTS += --enable-video-kmsdrm
 else
 SDL2_CONF_OPTS += --disable-video-kmsdrm