RFR: JDK-8027584 disable ccache by default

[Magnus Ihse Bursie]

Bug: https://bugs.openjdk.java.net/browse/JDK-8027584

While ccache can be used to speed up recompilations, there are also 
several issues with ccache. Old versions does not work correctly for the 
jdk (we try to detect that). It does not work well on other platforms 
than Linux; on Windows it does not work at all. Nevertheless is ccache 
enabled on Windows if it is installed, which it apparently tends to be 
with Cygwin nowadays, requiring the use of --disable-ccache to avoid 
compilation failure.

In many circumstances ccache also does not provide any performance 
benefit. For instance, new compilations gets a performance hit. Only 
recompilations benefits.

It is better to turn this upside down. This patch makes ccache disabled 
by default, on all platforms. If you want ccache and are sure you are in 
a situation that benefits from it, then you can enable it. It also 
removes the output in configure hinting that ccache should be used.

WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8027584-disable-ccache-by-default/webrev.01

/Magnus