Reserve some AIDs for OEMs

OEMs frequently add some AIDs on their own. Reserve some range
for them to use.

Change-Id: I3c729c889c9bd3e105ae4f6fb0c04a42a10eb25c

include/private/android_filesystem_config.h

@@ -83,6 +83,11 @@
 #define AID_CACHE         2001  /* cache access */
 #define AID_DIAG          2002  /* access to diagnostic resources */
 
+/* The range 2900-2999 is reserved for OEM, and must never be
+ * used here */
+#define AID_OEM_RESERVED_START 2900
+#define AID_OEM_RESERVED_END   2999
+
 /* The 3000 series are intended for use as supplemental group id's only.
  * They indicate special Android capabilities that the kernel is aware of. */
 #define AID_NET_BT_ADMIN  3001  /* bluetooth: create any socket */