Hookup the MCSymbolizer to llvm-objdump’s disassembly for Mach-O files.

First step done in this commit is to get flush out enough of the
SymbolizerGetOpInfo() routine to symbolic an X86_64 hello world .o and
its loading of the literal string and call to printf.  Also the code to
symbolicate the X86_64_RELOC_SUBTRACTOR relocation and a test is also
added to show a slightly more complicated case.

Next will be to flush out enough of SymbolizerSymbolLookUp() to get the
literal string “Hello world” printed as a comment on the instruction that load
the pointer to it.