using llvm's public 'C' disassembler API now including annotations.

Hooked this up to Darwin's otool(1) so it can again print things like branch
targets for example this:
 blx _puts
instead of this:
 blx #-36
and includes support for annotations for branches to symbol stubs like:
 bl	0x40 @ symbol stub for: _puts
and annotations for pc relative loads like this:
 ldr	r3, #8 @ literal pool for: Hello, world!
Also again can print the expression encoded in the Mach-O relocation entries for
things like this:
 movt r0, :upper16:((_foo-_bar)+1234)

llvm-svn: 141129