Update ext/aom submodule to 38711e7fe

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3762502..3b7f2e6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@
 - Remove all calls to `convertXYZToXYY()` as they were all unnecessary
 - Make calling `avifImageYUVToRGB()` upon reading an avif optional
 - Moved `ext/aom` submodule to use official remote
+- Update `ext/aom` submodule to commit [38711e7fe](https://aomedia.googlesource.com/aom/+/38711e7fe1eff68296b0324a9809804aec359fa5)
 
 ## [0.1.3] - 2019-04-23
 ### Changed

ext/aom

diff --git a/ext/aom b/ext/aom
index 3e3b934..38711e7 160000
--- a/ext/aom
+++ b/ext/aom
@@ -1 +1 @@
-Subproject commit 3e3b9342a20147ec6e4f89aa290e20277c1260ce
+Subproject commit 38711e7fe1eff68296b0324a9809804aec359fa5