hg: jdk9/sandbox: 8172712: configure should check that grep handles empty pattern correctly

[chris.hegarty at oracle.com]

Changeset: 0b6178060b7f
Author:    stuefe
Date:      2017-01-12 14:38 +0100
URL:       http://hg.openjdk.java.net/jdk9/sandbox/rev/0b6178060b7f

8172712: configure should check that grep handles empty pattern correctly
Reviewed-by: ihse

! common/autoconf/basics.m4
! common/autoconf/generated-configure.sh