Merge branch 'jk/push-client-deadlock-fix'

Some Windows SDK lacks pthread_sigmask() implementation and fails
to compile the recently updated "git push" codepath that uses it.

* jk/push-client-deadlock-fix:
  Windows: only add a no-op pthread_sigmask() when needed
  Windows: add pthread_sigmask() that does nothing

compat/mingw.h

@@ -142,6 +142,7 @@ static inline int fcntl(int fd, int cmd, ...)
 #define sigemptyset(x) (void)0
 static inline int sigaddset(sigset_t *set, int signum)
 { return 0; }
+#define SIG_BLOCK 0
 #define SIG_UNBLOCK 0
 static inline int sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
 { return 0; }

compat/win32/pthread.h

@@ -104,4 +104,11 @@ static inline void *pthread_getspecific(pthread_key_t key)
 	return TlsGetValue(key);
 }
 
+#ifndef __MINGW64_VERSION_MAJOR
+static inline int pthread_sigmask(int how, const sigset_t *set, sigset_t *oset)
+{
+	return 0;
+}
+#endif
+
 #endif /* PTHREAD_H */