wldap32: Handle null LDAPMessage in ldap_count_entries.

dlls/wldap32/misc.c

@@ -98,6 +98,7 @@ ULONG CDECL WLDAP32_ldap_count_entries( LDAP *ld, WLDAP32_LDAPMessage *res )
 {
     TRACE( "(%p, %p)\n", ld, res );
 
+    if (!res) return 0;
     if (!ld) return ~0u;
     return ldap_count_entries( CTX(ld), MSG(res) );
 }

dlls/wldap32/tests/parse.c

@@ -252,7 +252,13 @@ static void test_ldap_paged_search(void)
     ok( res != NULL, "expected res != NULL\n" );
     ok( count == 0, "got %lu\n", count );
 
-    count = ldap_count_entries( ld, res);
+    count = ldap_count_entries( NULL, NULL );
+    ok( count == 0, "got %lu\n", count );
+    count = ldap_count_entries( ld, NULL );
+    ok( count == 0, "got %lu\n", count );
+    count = ldap_count_entries( NULL, res );
+    todo_wine ok( count == 1, "got %lu\n", count );
+    count = ldap_count_entries( ld, res );
     ok( count == 1, "got %lu\n", count );
 
     entry = ldap_first_entry( ld, res);