FIH: Disable FIH labels on Apple targets

The symbols injected here cause some kind of poor interaction with the linker on
MacOS, which results in most of the code becoming hopelessly corrupt.  For now,
just disable these symbols on this target.

Signed-off-by: David Brown <david.brown@linaro.org>

boot/bootutil/include/bootutil/fault_injection_hardening.h

@@ -278,6 +278,8 @@ void fih_cfi_decrement(void);
  */
 #if defined(__ICCARM__)
 #define FIH_LABEL(str, lin, cnt) __asm volatile ("FIH_LABEL_" str "_" #lin "_" #cnt "::" ::);
+#elif defined(__APPLE__)
+#define FIH_LABEL(str) do {} while (0)
 #else
 #define FIH_LABEL(str) __asm volatile ("FIH_LABEL_" str "_%=:" ::);
 #endif