sunrpc: Use gid_valid to test for gid != INVALID_GID
sunrpc: Use gid_valid to test for gid != INVALID_GID

In auth unix there are a couple of places INVALID_GID is used a
sentinel to mark the end of uc_gids array.  Use gid_valid
as a type safe way to verify we have not hit the end of
valid data in the array.

Cc: "J. Bruce Fields" <51738506c1b2ccb0761f23bdc612c93babf738ea@fieldses.org>
Cc: Trond Myklebust <6a1f9db795c9fc44be97d66ab114c53193bd3d13@netapp.com>
Signed-off-by: "Eric W. Biederman" <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas