android: make symbols hidden by default

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

Android.common.mk

@@ -2,6 +2,7 @@
 LOCAL_CFLAGS += \
 	-DMAJOR_IN_SYSMACROS=1 \
 	-DHAVE_VISIBILITY=1 \
+	-fvisibility=hidden \
 	-DHAVE_LIBDRM_ATOMIC_PRIMITIVES=1
 
 LOCAL_CFLAGS += \