Avoid #include-ing fcntl.h and sys/stat.h in Random.cpp when not available (swiftlang#41279)

Author: kubamracek

stdlib/public/stubs/Random.cpp

@@ -22,15 +22,17 @@
 #include <Windows.h>
 #include <Bcrypt.h>
 #pragma comment(lib, "bcrypt.lib")
-#else
+#elif !defined(__APPLE__)
 #include <errno.h>
 #include <fcntl.h>
 #endif
 
 #if __has_include(<sys/random.h>)
 #include <sys/random.h>
 #endif
+#if __has_include(<sys/stat.h>)
 #include <sys/stat.h>
+#endif
 #if __has_include(<sys/syscall.h>)
 #include <sys/syscall.h>
 #endif