Upstream support for giflib >= 5.1. am: 4d4192b1e9 am: d904e5f707  -s ours am: b90915f511 am: e2fab03298 am: bea81784b8 am: 62307d39b8 am: d09659cb82 am: 4b97a3187d am: 332d95fe70 am: 9ed57f3006
am: e0fd32dd81

Change-Id: I31fb4681b29fb6d7c753016f5897c7a7d80a9c97