Fix MS-Windows build broken by 2011-07-08T20:39:30Z!eggert@cs.ucla.edu.

 src/w32.c (pthread_sigmask): New stub.

src/ChangeLog

+2011-07-09  Eli Zaretskii  <eliz@gnu.org>
+
+	* w32.c (pthread_sigmask): New stub.
+
 2011-07-08  Paul Eggert  <eggert@cs.ucla.edu>
 
 	Use pthread_sigmask, not sigprocmask (Bug#9010).

src/w32.c

@@ -1451,6 +1451,14 @@ sigprocmask (int how, const sigset_t *set, sigset_t *oset)
   return 0;
 }
 
+int
+pthread_sigmask (int how, const sigset_t *set, sigset_t *oset)
+{
+  if (sigprocmask (how, set, oset) == -1)
+    return EINVAL;
+  return 0;
+}
+
 int
 setpgrp (int pid, int gid)
 {