Properly handle WM_PAINT in dedicated server

Before this change window was constantly receiving WM_PAINT message
because it was not clearing its dirty region.
As a consequence of this change server console will be refreshed every
300 ms instead of every frame (default RF behavior).

Author: rafalh

docs/CHANGELOG.md

@@ -42,6 +42,7 @@ Version 1.9.0 (not released yet)
 - Add Kill Reward settings for dedicated servers
 - Do not load unnecessary VPPs in dedicated server mode
 - Add level filename to "Level Initializing" console message
+- Properly handle WM_PAINT in dedicated server, may improve performance (DF bug)
 
 Version 1.8.0 (released 2022-09-17)
 -----------------------------------

game_patch/os/os.cpp

@@ -71,9 +71,7 @@ LRESULT WINAPI wnd_proc(HWND wnd_handle, UINT msg, WPARAM w_param, LPARAM l_para
     case WM_PAINT:
         if (rf::is_dedicated_server)
             ++rf::console_redraw_counter;
-        else
-            return DefWindowProcA(wnd_handle, msg, w_param, l_param);
-        break;
+        return DefWindowProcA(wnd_handle, msg, w_param, l_param);
 
     default:
         return DefWindowProcA(wnd_handle, msg, w_param, l_param);