When the iOS SDK major version is 9 or higher:
- Pass -fembed-bitcode to compiler, assembler, and linker.
- Add a warning for simulator targets since yasm doesn't know
  what -fembed-bitcode means, and exits with an error.

BUG=https://code.google.com/p/webm/issues/detail?id=1075

Change-Id: I38c997a0225e53c5dd1b4ddf7935d21362953f76