Fixes the following building errors and resolves Bug 110922
Fixes gallium_dri target missing symbols at linking.

external/mesa/src/gallium/winsys/virgl/drm/Android.mk:
error: libmesa_winsys_virgl (STATIC_LIBRARIES android-x86_64) missing libmesa_winsys_virgl_common (STATIC_LIBRARIES android-x86_64)
...
external/mesa/src/gallium/winsys/virgl/vtest/Android.mk:
error: libmesa_winsys_virgl_vtest (STATIC_LIBRARIES android-x86_64) missing libmesa_winsys_virgl_common (STATIC_LIBRARIES android-x86_64)
...
build/core/main.mk:728: error: exiting from previous errors.

In file included from external/mesa/src/gallium/winsys/virgl/vtest/virgl_vtest_socket.c:34:
external/mesa/src/gallium/winsys/virgl/vtest/virgl_vtest_winsys.h:35:10:
fatal error: 'virgl_resource_cache.h' file not found
         ^~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

In file included from external/mesa/src/gallium/winsys/virgl/vtest/virgl_vtest_winsys.c:32:
external/mesa/src/gallium/winsys/virgl/vtest/virgl_vtest_winsys.h:35:10:
fatal error: 'virgl_resource_cache.h' file not found
#include "virgl_resource_cache.h"
         ^~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.

Fixes: b18f09a5

 ("virgl: Introduce virgl_resource_cache")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Tested-by: Clayton Craft <clayton.a.craft@intel.com>