sigsetmask.c was not processing the "mask" argument.

Change-Id: I79b898ea5b882e8c0564e25466e827a9bedda6e8
Author: yhe19 <yunan.he@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>

libc/unistd/sigsetmask.c

@@ -38,6 +38,8 @@ sigsetmask(int mask)
         sigset_t  the_sigset;
     } in, out;
 
+    in.the_mask = mask;
+
     n = sigprocmask(SIG_SETMASK, &in.the_sigset, &out.the_sigset);
     if (n)
         return n;