Add missing includes

<openssl/x509.h> is necessary to look into the X509 struct, used by
ac3ff8b1d8.

src/backend/libpq/be-secure-openssl.c

@@ -57,6 +57,7 @@
 #ifndef OPENSSL_NO_ECDH
 #include <openssl/ec.h>
 #endif
+#include <openssl/x509.h>
 
 #include "libpq/libpq.h"
 #include "miscadmin.h"

src/interfaces/libpq/fe-secure-openssl.c

@@ -58,6 +58,7 @@
 #ifdef USE_SSL_ENGINE
 #include <openssl/engine.h>
 #endif
+#include <openssl/x509.h>
 #include <openssl/x509v3.h>
 
 static bool verify_peer_name_matches_certificate(PGconn *);