Patch from the upstream git

kkos/oniguruma#57 (CVE-2017-9224)

Thanks to Mamoru TASAKA <mtasaka@fedoraproject.org>

Author: remicollet

ext/mbstring/oniguruma/regexec.c

@@ -1425,14 +1425,9 @@ match_at(regex_t* reg, const UChar* str, const UChar* end,
       break;
 
     case OP_EXACT1:  MOP_IN(OP_EXACT1);
-#if 0
       DATA_ENSURE(1);
       if (*p != *s) goto fail;
       p++; s++;
-#endif
-      if (*p != *s++) goto fail;
-      DATA_ENSURE(0);
-      p++;
       MOP_OUT;
       break;