minor, expand builddir and srcdir via readlink() and push to environment

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, drop shell variant xrealpath of realpath() and construct paths in ut-test binary instead

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
minor, also provide `testdir' environment variable with the absolute current wd

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
chore, make TS_TMPDIR absolute by means of ${testdir} in test suite

Signed-off-by: Sebastian Freundt <freundt@ga-group.nl>
Merge branch 'test/suite' into next

* test/suite:
  chore, make TS_TMPDIR absolute by means of ${testdir} in test suite
  minor, also provide `testdir' environment variable with the absolute current wd
  minor, drop shell variant xrealpath of realpath() and construct paths in ut-test binary instead
  minor, expand builddir and srcdir via readlink() and push to environment