Merge changes I32e726c7,I1dc9a708,I09cc335b,Ifb8a66ab,I0e2c25bc, ...
* changes:
versioner: whitelist atexit, turn on symbol checking by default.
versioner: add missing test.
versioner: fix false positive with functions only available as inlines.
versioner: improve error output slightly.
versioner: merge stdout and stderr in the test runner.
versioner: clean up tests, test runner.
versioner: ignore functions that are __INTRODUCED_IN_FUTURE.
versioner: autodetect paths when no specified.
versioner: improve usage messages.
Remove __cachectl.