Add support for "movsbl %sil,%ecx" (x86_64) and "movsbl $imm(%ebp), %edx"...

Add support for "movsbl %sil,%ecx" (x86_64) and "movsbl $imm(%ebp), %edx" (i386) to our fork of mach_override.
This is an extended version of a patch by Rafael Avila de Espindola (rafael.espindola@gmail.com)

llvm-svn: 161116