This document defines the coverage for function pthread_sigmask(). The functions pthread_sigmask() 
and sigprocmask() are equivalent functions, but pthread_sigmask() should also work in a
multi-threaded process. The tests in this section are similar in n nature to the tests for the
sigprocmask() function, but calls will be made from threads that belong to multi-threaded processes 
instead of single-threaded processes.

Assertion	Covered?
1		IMPLICITLY tested by assertions 1-18
2		WON'T test. Pertains only to sigprocmask().
3		IMPLICITLY tested by assertions 4-6
4		YES
5		YES
6		YES
7		YES
8		YES
9		YES
10		YES
11		WON'T test, because POSIX does not define behavior in this case.
12		YES
13		WON'T test, because POSIX does not define behavior in this case.
14		YES
15		WON'T test, pertains only to sigprocmask()
16		YES
17		WON'T test, pertains only to sigprocmask()
18		NO, won't test for now.
