Taught multiwatch to send the correct signal when using --signal

When the --signal flag was enabled, multiwatch was sending the
index of signal in the sig_actions array instead of the correct
signal number. So, when multiwatch was told to send a SIGTERM,
the application was actually being sent a SIGQUIT, which caused
the application to coredump as ordered.

The fix is to change the loop to return the signal number
stored at the index.

multiwatch.c

@@ -94,7 +94,7 @@ static gint signame2num(const char *name) {
 
 	for (i = 0; signal_actions[i].signame; i++) {
 		if (0 == strcmp(signal_actions[i].signame, name)) {
-			return i;
+			return signal_actions[i].signum;
 		}
 	}