Add Availability.h include to fix macOS SDK instrinsics
diff --git a/cs.c b/cs.c
index 2b53ac7..4f181c2 100644
--- a/cs.c
+++ b/cs.c
@@ -5,6 +5,7 @@
 #pragma warning(disable:28719)		// disable MSVC's warning on strcpy()
 #endif
 #if defined(CAPSTONE_HAS_OSXKERNEL)
+#include <Availability.h>
 #include <libkern/libkern.h>
 #else
 #include <stddef.h>