Typo.

src/conio/sdlfuncs.c

@@ -630,7 +630,7 @@ int SDL_main_env(int argc, char **argv, char **env)
 #ifdef _WIN32
 		/* Fail to windib (ie: No mouse attached) */
 		if(sdl.Init(SDL_INIT_VIDEO)) {
-			driver_env=getenv("SDL_VIDEODRIVER")==NULL)
+			driver_env=getenv("SDL_VIDEODRIVER");
 			if(driver_env==NULL || strcmp(driver_env,"windib")) {
 				putenv("SDL_VIDEODRIVER=windib");
 				WinExec(GetCommandLine(), SW_SHOWDEFAULT);