Non-tests/... changes:
- Add HAS_TESTS= to Makefiles with libraries and programs to enable iteration
and propagate the appropriate environment down to *.test.mk.
tests/... changes:
- Add appropriate support Makefile.inc's to set HAS_TESTS in a minimal manner,
since tests/... is a special subdirectory tree compared to the others.
MFC after: 2 months
MFC with: r322511
Reviewed by: arch (silence), testing (silence)
Differential Revision: D12014
18951eee49