Activated some stubs for SDL port. Someone should implement them in future, but for now it should at least compile.

src/platform/StdSDLApp.cpp

@@ -172,8 +172,6 @@ bool CStdApp::SetVideoMode(unsigned int iXRes, unsigned int iYRes, unsigned int
 void CStdApp::RestoreVideoMode() {
 }
 
-#ifndef __APPLE__
-
 // stubs
 
 void CStdApp::Copy(const StdStrBuf & text, bool fClipboard) {
@@ -194,8 +192,6 @@ void CStdApp::MessageDialog(const char * message)
 {
 }
 
-#endif
-
 // Event-pipe-whatever stuff I do not understand.
 
 bool CStdApp::ReadStdInCommand() {

src/platform/StdSDLWindow.cpp

@@ -76,7 +76,5 @@ void CStdWindow::SetTitle(const char * Title) {
 	SDL_WM_SetCaption(Title, 0);
 }
 
-#ifndef __APPLE__
 void CStdWindow::FlashWindow() {
 }
-#endif