Add a flag to use panda-specific gfx libs

Change-Id: I530cf889c4a3806f3daedd1169826bc377aebb17
diff --git a/BoardConfig.mk b/BoardConfig.mk
index 14fad4d..1ce603c 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -44,6 +44,7 @@
 #BOARD_USES_HGL := true
 #BOARD_USES_OVERLAY := true
 USE_OPENGL_RENDERER := true
+BOARD_USES_PANDA_GRAPHICS := true
 
 TARGET_USERIMAGES_USE_EXT4 := true
 BOARD_SYSTEMIMAGE_PARTITION_SIZE := 268435456