ffmpeg: revision for x265

Formula/ffmpeg.rb

@@ -3,6 +3,7 @@ class Ffmpeg < Formula
   homepage "https://ffmpeg.org/"
   url "https://ffmpeg.org/releases/ffmpeg-4.2.1.tar.xz"
   sha256 "cec7c87e9b60d174509e263ac4011b522385fd0775292e1670ecc1180c9bb6d4"
+  revision 1
   head "https://github.com/FFmpeg/FFmpeg.git"
 
   bottle do
@@ -43,6 +44,10 @@ class Ffmpeg < Formula
   depends_on "xz"
 
   def install
+    # Work around Xcode 11 clang bug
+    # https://bitbucket.org/multicoreware/x265/issues/514/wrong-code-generated-on-macos-1015
+    ENV.append_to_cflags "-fno-stack-check" if DevelopmentTools.clang_build_version >= 1010
+
     args = %W[
       --prefix=#{prefix}
       --enable-shared