Tests: Update for upstream ninja change to write status on stderr
Upstream ninja commit
ad3d29fb53 (Put builder output through status
interface) from ninja PR 1899 changed the status output from stdout to
stderr. In particular,
ninja: no work to do is now printed on stderr.
Update our RunCMake tests to accept this difference.
A few RunCMake test cases check for
ninja: no work to do. For those,
move the message to stdout using
RunCMake_TEST_OUTPUT_MERGE. The rest
of the test cases do not care about the message, so remove it from the
actual stderr content before comparing against that expected.