EC_GROUP_cmp should return zero if the groups match.

(I got this wrong when reading the OpenSSL code.)

(Cherry-picked form upstream BoringSSL's
7c21925a10d451ed13ab201e0161dea40b974397)

Change-Id: Icedaa45c9d17e7c2b95fa5be1f7c0bf41cac0880
diff --git a/src/include/openssl/ec.h b/src/include/openssl/ec.h
index f915635..eb9a153 100644
--- a/src/include/openssl/ec.h
+++ b/src/include/openssl/ec.h
@@ -115,7 +115,7 @@
  * error. */
 OPENSSL_EXPORT EC_GROUP *EC_GROUP_dup(const EC_GROUP *a);
 
-/* EC_GROUP_cmp returns one if |a| and |b| are the same group and zero
+/* EC_GROUP_cmp returns zero if |a| and |b| are the same group and non-zero
  * otherwise. */
 OPENSSL_EXPORT int EC_GROUP_cmp(const EC_GROUP *a, const EC_GROUP *b,
                                 BN_CTX *ignored);