Allow showing version only for SDL

SDL/SDLMain.cpp

@@ -448,6 +448,13 @@ static void EmuThreadJoin() {
 #undef main
 #endif
 int main(int argc, char *argv[]) {
+	for (int i = 1; i < argc; i++) {
+		if (!strcmp(argv[i], "--version")) {
+			printf("%s\n", PPSSPP_GIT_VERSION);
+			return 0;
+		}
+	}
+
 	glslang::InitializeProcess();
 
 #if PPSSPP_PLATFORM(RPI)