Add macOS ARM64 build support

Three small source tweaks that let the OpenGL renderer build and run
on Apple Silicon without affecting the Windows/Linux paths:

- stdafx.h: use GLM_FORCE_NEON on ARM64 instead of GLM_FORCE_AVX2.
  AVX2 pulls <immintrin.h>, which clang on ARM64 rejects because
  the x86 intrinsics are unimplemented.
- utilities/utilities.cpp: provide an Apple libc++ fallback for
  Now() using localtime_r + strftime, since
  std::chrono::current_zone() is not yet implemented there.
- audio/audio.h: prefer Khronos-style <AL/al.h> headers when they
  are on the include path (brew openal-soft) and fall back to the
  deprecated Apple OpenAL.framework's <OpenAL/al.h> only otherwise.

utilities/utilities.cpp

@@ -39,9 +39,18 @@ bool DebugTractionFlag = false;
 
 std::string Now()
 {
+#if defined(__APPLE__)
+	auto t = std::chrono::system_clock::to_time_t(std::chrono::system_clock::now());
+	std::tm tm{};
+	localtime_r(&t, &tm);
+	char buf[64];
+	std::strftime(buf, sizeof(buf), "%c", &tm);
+	return std::string(buf);
+#else
 	auto now = std::chrono::system_clock::now();
 	auto local = std::chrono::current_zone()->to_local(now);
 	return std::format("{:%c}", local);
+#endif
 }
 
 // zwraca różnicę czasu