hg: build-infra/jdk8: Check that source directories provided to SetupJava/NativeCompilation actually exist.

[magnus.ihse.bursie at oracle.com]

Changeset: 6775b3657311
Author:    ihse
Date:      2012-10-23 14:22 +0200
URL:       http://hg.openjdk.java.net/build-infra/jdk8/rev/6775b3657311

Check that source directories provided to SetupJava/NativeCompilation actually exist.

! common/makefiles/JavaCompilation.gmk
! common/makefiles/NativeCompilation.gmk