hg: panama/panama/jdk: Disable libclang if not available

[henry.jen at oracle.com]

Changeset: 127081373ebe
Author:    henryjen
Date:      2014-11-12 15:26 -0800
URL:       http://hg.openjdk.java.net/panama/panama/jdk/rev/127081373ebe

Disable libclang if not available

! make/CreateJars.gmk
! make/lib/Lib-java.base.gmk
+ src/jdk.dev/share/classes/com/sun/tools/jextract/Utils.java