Re-add support to llvm-objdump for Mach-O universal files and archives with -macho

Re-add support to llvm-objdump for Mach-O universal files and archives with -macho
with fixes.  Includes the move of tests for llvm-objdump for universal files to an X86
directory.  And the fix where it was failing on linux Rafael tracked down with asan.
I had both Jim Grosbach and Adam Hemet look over the second fix since I could not
set up asan to reproduce with the old version but not with the fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223416 91177308-0d34-0410-b5e6-96231b3b80d8