update ChangeLog

Bug: webp:608
Change-Id: Id619a5e39a71d1372fd2209774f4f57d87712aa7

Author: jzern

ChangeLog

@@ -1,3 +1,13 @@
+e1adea50 update NEWS
+43393320 enc/*: normalize WebPEncodingSetError() calls
+287fdefe enc/*: add missing WebPEncodingSetError() calls
+c3bd7cff EncodeAlphaInternal: add missing error check
+d49cfbb3 vp8l_enc,WriteImage: add missing error check
+2e5a9ec3 muxread,MuxImageParse: add missing error checks
+ebb6f949 cmake,emscripten: explicitly set stack size
+59a2b1f9 WebPDecodeYUV: check u/v/stride/uv_stride ptrs
+8e965ccb Call png_get_channels() to see if image has alpha
+7f0a3419 update ChangeLog (tag: v1.3.1-rc1)
 bab7efbe update NEWS
 7138bf8f bump version to 1.3.1
 435b4ded update AUTHORS