Fix old file reference in gcc/cp/cp-gimplify.c

I've found this stale reference while looking at cp-gimplify.c. tree-gimple.c
no longer exists and its contents were merged into gimple.c.

Seems obvious enough.

gcc/cp/ChangeLog:

2019-10-16  Luis Machado  <luis.machado@linaro.org>

	* cp-gimplify.c: Fix reference to non-existing tree-gimple.c file.

From-SVN: r277089

gcc/cp/ChangeLog

+2019-10-16  Luis Machado  <luis.machado@linaro.org>
+
+	* cp-gimplify.c: Fix reference to non-existing tree-gimple.c file.
+
 2019-10-16  Jakub Jelinek  <jakub@redhat.com>
 
 	* decl.c (cxx_maybe_build_cleanup): When clearing location of cleanup,

gcc/cp/cp-gimplify.c

-/* C++-specific tree lowering bits; see also c-gimplify.c and tree-gimple.c.
+/* C++-specific tree lowering bits; see also c-gimplify.c and gimple.c.
 
    Copyright (C) 2002-2019 Free Software Foundation, Inc.
    Contributed by Jason Merrill <jason@redhat.com>