FindThreads: Reduce amount of false positive error logging
When a CMake based project fails, users start looking at CMakeError.log and think that the FindThread output is the problem, but it is a false positive.
Now FindThreads only logs to CMakeError.log
when it fails
to find a suitable flag, reducing the amount of false positives in CMakeError.log
.
Fixes: #16540 (closed), #19344 (closed)
Edited by Robert Maynard