hg: jdk/submit12: 8215400: Warn on usage of trampolines with gcc

[erik.joelsson at oracle.com]

Changeset: 8970b75f0d37
Author:    erikj
Date:      2019-01-07 10:00 +0100
URL:       http://hg.openjdk.java.net/jdk/submit12/rev/8970b75f0d37

8215400: Warn on usage of trampolines with gcc
Reviewed-by: tbell, kbarrett

! make/autoconf/flags-cflags.m4