Fix warning where BIO_FLAGS_UPLINK was being redefined.
This warning breaks the build in 1.0.0 and 0.9.8

Reviewed-by: Andy Polyakov <appro@openssl.org>

crypto/ecdsa/ecs_vrf.c

diff --git a/crypto/ecdsa/ecs_vrf.c b/crypto/ecdsa/ecs_vrf.c
index 7191b8a..2a350eb 100644
--- a/crypto/ecdsa/ecs_vrf.c
+++ b/crypto/ecdsa/ecs_vrf.c
@@ -57,7 +57,7 @@
  */
 
 #include "ecs_locl.h"
-#include "cryptlib.h"
+#include <string.h>
 #ifndef OPENSSL_NO_ENGINE
 #include <openssl/engine.h>
 #endif