Add missing file expected with rev 279781

            * config/vxworks-c.c: New file.

From-SVN: r279790

gcc/config/vxworks-c.c

+/* C-family target hooks initializer for VxWorks targets.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "c-family/c-target.h"
+#include "c-family/c-target-def.h"
+
+/* Implement TARGET_C_PREINCLUDE for vxworks targets.  */
+
+static const char *
+vxworks_c_preinclude (void)
+{
+  return "vxworks-predef.h";
+}
+
+#undef TARGET_C_PREINCLUDE
+#define TARGET_C_PREINCLUDE vxworks_c_preinclude
+
+struct gcc_targetcm targetcm = TARGETCM_INITIALIZER;