First batch of changes from FailSafeC

This is all tiny stuff - allow overriding WIDENED_PROTOTYPES from the hints
file, missing NO_SIGNAL conditionals, remove a GCC-ism, conditional indentation,
void return in a non-void function.

sys/share/ioctl.c

@@ -162,10 +162,10 @@ dosuspend()
 	   || !check_user_string(sysopt.shellers)
 	){
 		Norep("Suspend command not available.");
-		return;
+		return 0;
 	}
 #endif
-# ifdef SIGTSTP
+# if defined(SIGTSTP) && !defined(NO_SIGNAL)
 	if(signal(SIGTSTP, SIG_IGN) == SIG_DFL) {
 		suspend_nhwindows((char *)0);
 #  ifdef _M_UNIX