Make sure $$relative_path() uses an absolute path as its first arg

Thanks to QTBUG-61373, this qmake function was called with
/usr/local/5.10.1 as baseDir, which isn't absolute, leading to an
assertion failure.  We could raise the error within qmake but it
proved easier to simply resolve any non-absolute baseDir using PWD,
before trying to use it as an absolute path.

Did the same for $$absolute_path().  Documented both.  Adjusted the
assert that caught this to report any non-absolute path that upsets
it.  Added simple tests, fixed an existing test.

Task-number: QTBUG-66156
Change-Id: Icfef2e2f5b236e071177c9beffa38d71bf404292
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

0 files changed, 0 insertions, 0 deletions