Bug 1869332 - Write a placeholder implementation for getting the buildconfig. r=chunmin

This is expected to be present in ffmpeg, but is only for displaying things on
the command-line, we don't need a "real" implementation.

Differential Revision: https://phabricator.services.mozilla.com/D196062

media/libaom/build_config.c

@@ -0,0 +1,8 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Placeholder implementation -- need to be present but not used
+const char *aom_codec_build_config(void) {return "It's a good config.";}

media/libaom/moz.build

@@ -95,6 +95,8 @@ for f in SOURCES:
     elif f.endswith('avx2.c'):
         SOURCES[f].flags += ['-mavx2']
 
+SOURCES += [ 'build_config.c' ]
+
 # Suppress warnings in third-party code.
 CFLAGS += [
     '-Wno-sign-compare',