Switch aom submodule to use official remote

.gitmodules

diff --git a/.gitmodules b/.gitmodules
index 351c322..e3494ed 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "ext/aom"]
 	path = ext/aom
-	url = https://github.com/joedrago/aom.git
+	url = https://aomedia.googlesource.com/aom

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3621be3..3762502 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 - `avifenc` and `avifdec` "apps" which show basic bidirectional conversion to y4m
 - 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
 
 ## [0.1.3] - 2019-04-23
 ### Changed

ext/CMakeLists.txt

diff --git a/ext/CMakeLists.txt b/ext/CMakeLists.txt
index a4f038b..45325c2 100644
--- a/ext/CMakeLists.txt
+++ b/ext/CMakeLists.txt
@@ -1,8 +1,12 @@
 # Copyright 2019 Joe Drago. All rights reserved.
 # SPDX-License-Identifier: BSD-2-Clause
 
-set(AOM_MINIMAL_BUILD TRUE)
-add_subdirectory(aom)
+set(ENABLE_DOCS 0)
+set(ENABLE_EXAMPLES 0)
+set(ENABLE_TESTDATA 0)
+set(ENABLE_TESTS 0)
+set(ENABLE_TOOLS 0)
+add_subdirectory(aom EXCLUDE_FROM_ALL)
 
 if(NOT AVIF_EXTERNAL_GB)
 include_directories(gb)