Merge pull request #35 from github/inspec-ivar-segv

Stop reading past the end of `ivptr` array

Author: Vicent Martí

variable.c

@@ -1605,7 +1605,7 @@ rb_ivar_count(VALUE obj)
     switch (BUILTIN_TYPE(obj)) {
       case T_OBJECT:
 	if ((tbl = ROBJECT_IV_INDEX_TBL(obj)) != 0) {
-	    st_index_t i, count, num = tbl->num_entries;
+	    st_index_t i, count, num = ROBJECT_NUMIV(obj);
 	    const VALUE *const ivptr = ROBJECT_IVPTR(obj);
 	    for (i = count = 0; i < num; ++i) {
 		if (ivptr[i] != Qundef) {