Make simulator compile on MacOS

Tested on MacOS Sequoia (Apple Silicon) with the
latest Xcode command line tools, gcc 14
(Homebrew GCC 14.2.0_1) and sdl2 (Homebrew 2.30.9)

Make sure 'gcc' (and 'gcc-ar') is in your PATH
ahead of the Xcode-provided "gcc"(clang). E.g.
by setting up symlinks in /usr/local/bin that
point to gcc-14 and gcc-ar-14.

Notes:
- The appropriate bmp from uisimulator/bitmaps
  has to be manually copied to your build folder
  and renamed to UI256.bmp, if you want the sim
  background to be displayed

Change-Id: I559f33d2165065f913f30c016b85906af380fb81

firmware/include/rbendian.h

@@ -28,8 +28,12 @@
 #endif
 
 #ifndef __MINGW32__
+#ifdef __APPLE__
+#include <sys/types.h>
+#else
 #include <endian.h>
 #endif
+#endif
 
 /* clear these out since we redefine them to be truely constant compatible */
 #undef swap16