Reland "[lld-macho] Show source information for undefined references"

The error used to look like this:

  ld64.lld: error: undefined symbol: _foo
  >>> referenced by /path/to/bar.o:(symbol _baz+0x4)

If DWARF line information is available, we now show where in the source
the references are coming from:

  ld64.lld: error: unreferenced symbol: _foo
  >>> referenced by: bar.cpp:42 (/path/to/bar.cpp:42)
  >>>                /path/to/bar.o:(symbol _baz+0x4)

The reland is identical to the first time this landed. The fix was in D128294.
This reverts commit 0cc7ad41.

Differential Revision: https://reviews.llvm.org/D128184