hg: jdk/sandbox: 8196365: Overriding configure variable from custom hook generates warning

[chris.hegarty at oracle.com]

Changeset: 2e2551c38484
Author:    erikj
Date:      2018-01-29 17:08 -0800
URL:       http://hg.openjdk.java.net/jdk/sandbox/rev/2e2551c38484

8196365: Overriding configure variable from custom hook generates warning
Reviewed-by: tbell

! make/autoconf/basics.m4
! make/autoconf/configure.ac
! make/autoconf/generated-configure.sh