Add dsymutil dwarf5 tests for darwin

The first test, dwarf5-macho.test checks to make sure that dsymutil
generates the correct headers and sections for a macho binary with
DWARF v5 in it.

The second test, dwarf5-dwarf4-combination-macho.test checks that
dsymutil generates the correct headers and sections for a macho binary
with which was linked with one object file with DWARF v4 and the other
with DWARF v5 in it.

Differential Revision: https://reviews.llvm.org/D151932