py/nlrthumb: Add support for iOS where the C func is _nlr_push_tail.

py/nlrthumb.c

@@ -71,9 +71,13 @@ __attribute__((naked)) unsigned int nlr_push(nlr_buf_t *nlr) {
     "bx     r1                  \n" // do the rest in C
     ".align 2                   \n"
     "nlr_push_tail_var: .word nlr_push_tail \n"
+#else
+    #if defined(__APPLE__) || defined(__MACH__)
+    "b      _nlr_push_tail      \n" // do the rest in C
     #else
     "b      nlr_push_tail       \n" // do the rest in C
     #endif
+#endif
     );
 
     #if !defined(__clang__) && defined(__GNUC__) && (__GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8))