Convert CRYPTO_LOCK_EVP_PKEY to new multi-threading API

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>

crypto/include/internal/evp_int.h

@@ -416,6 +416,7 @@ struct evp_pkey_st {
     } pkey;
     int save_parameters;
     STACK_OF(X509_ATTRIBUTE) *attributes; /* [ 0 ] */
+    CRYPTO_RWLOCK *lock;
 } /* EVP_PKEY */ ;