[Chromecast] Don't export symbols from libffmpeg.a

build/config/chromecast/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chromecast_build.gni")
 
 assert(is_chromecast)
 
 config("static_config") {
   ldflags = [
     # We want to statically link libstdc++/libgcc.
     "-static-libstdc++",
     "-static-libgcc",
+    # Don't allow visible symbols from libraries that contain
+    # assembly code with symbols that aren't hidden properly.
+    # http://b/26390825
+    '-Wl,--exclude-libs=libffmpeg.a',
   ]
 }
 
 config("executable_config") {
   if (current_cpu == "arm") {
     ldflags = [
       # Export stdlibc++ and libgcc symbols to force shlibs to refer to these
       # symbols from the executable.
       "-Wl,--export-dynamic",
 
@@ skipping 13 matching lines @@
     # dynamic dependency on them.
     configs = [ ":static_config" ]
   }
 }
 
 config("shared_library_config") {
   if (current_cpu == "arm") {
     configs = [ ":static_config" ]
   }
 }