Update libwebp to 1.0.2-rc1

Android is updating [1]. Run our tests on this version as well.

[1] https://android-review.googlesource.com/c/platform/external/webp/+/872756

Change-Id: I38ed1a633ba457df59729321551c09920be35910
Reviewed-on: https://skia-review.googlesource.com/c/184801
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
diff --git a/DEPS b/DEPS
index fc686a0..4d60d86 100644
--- a/DEPS
+++ b/DEPS
@@ -19,7 +19,7 @@
   "third_party/externals/jsoncpp"         : "https://chromium.googlesource.com/external/github.com/open-source-parsers/jsoncpp.git@1.0.0",
   "third_party/externals/libjpeg-turbo"   : "https://skia.googlesource.com/external/github.com/libjpeg-turbo/libjpeg-turbo.git@2.0.0",
   "third_party/externals/libpng"          : "https://skia.googlesource.com/third_party/libpng.git@v1.6.33",
-  "third_party/externals/libwebp"         : "https://chromium.googlesource.com/webm/libwebp.git@v1.0.1",
+  "third_party/externals/libwebp"         : "https://chromium.googlesource.com/webm/libwebp.git@v1.0.2-rc1",
   "third_party/externals/lua"             : "https://skia.googlesource.com/external/github.com/lua/lua.git@v5-3-4",
   "third_party/externals/microhttpd"      : "https://android.googlesource.com/platform/external/libmicrohttpd@748945ec6f1c67b7efc934ab0808e1d32f2fb98d",
   "third_party/externals/opencl-lib"      : "https://skia.googlesource.com/external/github.com/GPUOpen-Tools/common-lib-amd-APPSDK-3.0@4e6d30e406d2e5a65e1d65e404fe6df5f772a32b",
diff --git a/third_party/libwebp/BUILD.gn b/third_party/libwebp/BUILD.gn
index 6975e50..cdb645f 100644
--- a/third_party/libwebp/BUILD.gn
+++ b/third_party/libwebp/BUILD.gn
@@ -82,6 +82,7 @@
       "../externals/libwebp/src/dsp/cost.c",
       "../externals/libwebp/src/dsp/cost_mips32.c",
       "../externals/libwebp/src/dsp/cost_mips_dsp_r2.c",
+      "../externals/libwebp/src/dsp/cost_neon.c",
       "../externals/libwebp/src/dsp/cost_sse2.c",
       "../externals/libwebp/src/dsp/cpu.c",
       "../externals/libwebp/src/dsp/dec.c",