update to v1.1.0-8-g50f60add

https://chromium.googlesource.com/webm/libwebp/+log/v1.1.0..v1.1.0-8-g50f60add

50f60add Fix OOB write in BuildHuffmanTable.
5df85e9c EncodeAlphaInternal: clear result->bw on error
89e226a3 GetBackwardReferences: fail on alloc error
4d0964cd BackwardReferencesHashChainDistanceOnly: fix segfault on OOM
5d805f72 VP8LEncodeStream: fix segfault on OOM
b14eba64 alpha_processing_neon.c: fix 0x01... typo
9183ff2e alpha_processing_neon.c: fix Dispatch/ExtractAlpha_NEON
68d52453 Fix lossless encoding for MIPS.

Bug: 299477569
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:c3f928a1d30e48a400ed434130da3609cbfd54ad)
Merged-In: Ia4290d2a5f16a61ae0729b7d55ba144251c2b988
Change-Id: Ia4290d2a5f16a61ae0729b7d55ba144251c2b988
12 files changed