Fix a crash with malformed user notice policy numbers

(Imported from upstream's efe8398649a1d7fc9d84d2818592652e0632a8a8.)

Change-Id: I0d04b3e75ec26a7dd3a7af31b0e115723c4b24d9
Reviewed-on: https://boringssl-review.googlesource.com/13661
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>

crypto/x509v3/v3_cpols.c

@@ -400,10 +400,10 @@ static int nref_nos(STACK_OF(ASN1_INTEGER) *nnums, STACK_OF(CONF_VALUE) *nos)
     return 1;
 
  merr:
+    ASN1_INTEGER_free(aint);
     OPENSSL_PUT_ERROR(X509V3, ERR_R_MALLOC_FAILURE);
 
  err:
-    sk_ASN1_INTEGER_pop_free(nnums, ASN1_STRING_free);
     return 0;
 }