events: Buildfix for targets with C++ build units

src/events/SDL_windowevents_c.h

@@ -23,6 +23,11 @@
 #ifndef SDL_windowevents_c_h_
 #define SDL_windowevents_c_h_
 
+// Set up for C function definitions, even when using C++
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef enum
 {
     SDL_WINDOW_EVENT_WATCH_EARLY,
@@ -36,4 +41,9 @@ extern void SDL_RemoveWindowEventWatch(SDL_WindowEventWatchPriority priority, SD
 
 extern bool SDL_SendWindowEvent(SDL_Window *window, SDL_EventType windowevent, int data1, int data2);
 
+// Ends C function definitions when using C++
+#ifdef __cplusplus
+}
+#endif
+
 #endif // SDL_windowevents_c_h_