android: util/disk_cache: fix building errors in gallium drivers

This patch applies the necessary changes in Android.common.mk
as per automake rules, to avoid following building error:

external/mesa/src/gallium/drivers/nouveau/nouveau_screen.c:159:8:
error: implicit declaration of function 'disk_cache_get_function_timestamp'
is invalid in C99 [-Werror,-Wimplicit-function-declaration]
   if (disk_cache_get_function_timestamp(nouveau_disk_cache_create,
       ^
1 error generated.

(v2) -DENABLE_SHADER_CACHE Android cflag is kept, to leave the AS-IS capability enabled

Fixes: cc10b34e ("util/disk_cache: Fix disk_cache_get_function_timestamp with disabled cache.")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit 6cbbd5b4)