//	    Write a mutex contention profile to the specified file
//	    when all tests are complete.
//	    Writes test binary as -c would.
//
//	-mutexprofilefraction n
//	    Sample 1 in n stack traces of goroutines holding a
//	    contended mutex.
//
//	-outputdir directory
//	    Place output files from profiling in the specified directory,
//	    by default the directory in which "go test" is running.