This document defines the coverage for the pthread_mutex_destroy function:

Assertion	Tested?
1		YES
2		YES
3		YES
4		NO ** Keeping in mind it 'may' fail and not 'shall' fail,
		      so it will always return PASS, but will return a
		      PASS and print out a warning if it fails.
		   ** EBUSY is tested
5		YES
NOTE: