Added support for building SDL as a dynamic library on iOS

src/main/uikit/SDL_uikit_main.c

@@ -0,0 +1,19 @@
+/*
+    SDL_uiki_main.c, placed in the public domain by Sam Lantinga  3/18/2019
+*/
+#include "../../SDL_internal.h"
+
+/* Include the SDL main definition header */
+#include "SDL_main.h"
+
+#ifdef main
+#undef main
+#endif
+
+int
+main(int argc, char *argv[])
+{
+    return SDL_UIKitRunApp(argc, argv, SDL_main);
+}
+
+/* vi: set ts=4 sw=4 expandtab: */