Return DiffStatus from FilterOutRenamedRecordFields

The status of the filtered out fields is either kNoDiff or
kIndirectDiff. It does not affect the diff report, but makes
ModuleMerger determine redefined types more accurately.

Test: ./test.py ; update the prebuilt clang tools and build
Bug: 255702405
Change-Id: Ia94225d25e00597affa8b1e01a7c9de592bf5b05
2 files changed