Convert from the C-based LLVM Disassembler shim to the full MC Disassembler API's.

Calculate "can branch" using the MC API's rather than our hand-rolled regex'es.
As extra credit, allow setting the disassembly flavor for x86 based architectures to intel or att.

<rdar://problem/11319574>
<rdar://problem/9329275>

llvm-svn: 176392