Hopefully make macOS port compatible with SDL3

.. mostly by not making it use SDL_main.h, because it implements its
own SDL main functionality anyway.

However, I have no way to test this code and as long as SDL3 is not in
homebrew testing it in the CI build isn't easy either.

neo/sys/osx/DOOMController.mm

@@ -32,9 +32,6 @@
 #include <fenv.h>
 #include <mach/thread_status.h>
 #include <AppKit/AppKit.h>
-
-#include <SDL_main.h>
-
 #include "sys/platform.h"
 
 #include <sys/types.h>
@@ -194,13 +191,15 @@ int SDL_main( int argc, char *argv[] ) {
 		Sys_Error("Could not access application resources");
 
 	// DG: set exe_path so Posix_InitSignalHandlers() can call Posix_GetExePath()
-	SDL_strlcpy(exe_path, [ [ [ NSBundle mainBundle ] bundlePath ] cStringUsingEncoding:NSUTF8StringEncoding ], sizeof(exe_path));
+	strncpy(exe_path, [ [ [ NSBundle mainBundle ] bundlePath ] cStringUsingEncoding:NSUTF8StringEncoding ], sizeof(exe_path)-1);
+	exe_path[sizeof(exe_path)-1] = '\0';
 	// same for save_path for Posix_GetSavePath()
 	D3_snprintfC99(save_path, sizeof(save_path), "%s/Library/Application Support/dhewm3", [NSHomeDirectory() cStringUsingEncoding:NSUTF8StringEncoding]);
 	// and preinitializing basepath is easy enough so do that as well
 	{
 		char* snap;
-		SDL_strlcpy(base_path, exe_path, sizeof(base_path));
+		strncpy(base_path, exe_path, sizeof(base_path)-1);
+		base_path[sizeof(base_path)-1] = '\0';
 		snap = strrchr(base_path, '/');
 		if (snap)
 			*snap = '\0';

neo/sys/osx/SDLMain.m

@@ -10,7 +10,15 @@
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 #endif
 
-#include "SDL.h"
+#ifdef D3_SDL3
+  #include <SDL3/SDL.h>
+  // as SDL.h doesn't implicitly include SDL_main.h anymore,
+  // declare SDL_main() here. I think it's the only part of SDL_main.h we used,
+  // we implement it in DOOMController.mm an call it here in applicationDidFinishLaunching
+  extern int SDL_main( int argc, char *argv[] );
+#else // SDL2 and SDL1.2
+  #include "SDL.h"
+#endif
 #include "SDLMain.h"
 #include <sys/param.h> /* for MAXPATHLEN */
 #include <unistd.h>