hg: jdk7/build: 6909026: Change GNU make version requirement to 3.81

[kelly.ohair at oracle.com]

Changeset: f4c95f4b7590
Author:    ohair
Date:      2010-12-18 18:28 -0800
URL:       http://hg.openjdk.java.net/jdk7/build/rev/f4c95f4b7590

6909026: Change GNU make version requirement to 3.81
Reviewed-by: robilad

! README
! README-builds.html