log/windows: Don't call logging facilities during static var destruction

This is UB and a sure recipe for disaster if log.o's variables are
destructed first. The message is superfluous and not actually intended
to be displayed in normal use (hence debug level), so let's just not
poke dead men walking.

src/log_windows.cpp

@@ -316,7 +316,6 @@ log_file_manager::~log_file_manager()
 		return;
 	}
 
-	DBG_LS << "Closing log file...\n";
 	fclose(stdout);
 	fclose(stderr);
 }