Look up referenced types' compilation unit paths when linking ABI dumps

When header-abi-linker merges a pointer, reference, array, or qualified
type, it looks up the referenced type's compilation unit path, and uses
the path to distinguish multiple definitions of the type as well as the
types referencing it.

Test: ./test.py
Bug: 147396457
Change-Id: If6b35e941f9aa03616b236289450c9b10062b719
3 files changed