Flush out enough of llvm-objdump’s SymbolizerSymbolLookUp() for Mach-O files to

get the literal string “Hello world” printed as a comment on the instruction
that loads the pointer to it. For now this is just for x86_64. So for object
files with relocation entries it produces things like:

	leaq	L_.str(%rip), %rax      ## literal pool for: "Hello world\n"

and similar for fully linked images like executables:

	leaq	0x4f(%rip), %rax        ## literal pool for: "Hello world\n"

Also to allow testing against darwin’s otool(1), I hooked up the existing 
-no-show-raw-insn option to the Mach-O parser code, added the new Mach-O
only -full-leading-addr option to match otool(1)'s printing of addresses and
also added the new -print-imm-hex option.

llvm-svn: 218423