RFR: 8014074: Building hotspot with ccache in new build is very slow with empty cache.

[Erik Joelsson]

This patch to configure disables precompiled headers in hotspot when 
ccache is in use.

Background is in this mail (and the bug report):
http://mail.openjdk.java.net/pipermail/build-dev/2013-April/008772.html

In short, build time is shortened considerably both with an empty and a 
perfect cache when ccache is in use.

Note that this only affects full builds from the root repo and not 
hotspot only builds.

http://cr.openjdk.java.net/~erikj/8014074/webrev.root.01/

/Erik