Reduce size of pause_window::msg

1024 is excessive.  128 leaves 25 bytes unused on Trainee (the longest
difficulty string, tied with Hotshot) at time 0:00:00.  A player who
reached double-digit hours for both time on level and time in game would
need 2 bytes more.  A player who rescued 100 hostages would need another
2 bytes.

similar/main/gamecntl.cpp

@@ -125,7 +125,7 @@ namespace {
 struct pause_window : window
 {
 	using window::window;
-	std::array<char, 1024> msg;
+	std::array<char, 128> msg;
 };
 
 }