FreeBSD ccache port is wonderfiul!

[tridge at samba.org]

Andrew,

 > By saying "to go into production" I meant this:
 > ccache is based on such a great idea, that it is
 > a wonder that it haven't been integrated into
 > build processes such as buildworld or even gcc
 > itself yet. As we can see, there are some problems
 > with using ccache in production.

I think its more a matter of people finding that the compiler
bootstrapping process used in buildworld is not necessary in some
cases. But there are cases where it is necessary, and then the various
tricks used to avoid it come unstuck. As I suggested to Jens, there
should perhaps be a way to disable the bootstrapping in buildworld,
then when people get a build failure with the bootstrapping off they
can try again with full compiler bootstrapping (which will be slower
of course).

Meanwhile, the CCACHE_HASH_COMPILER patch I just put in should give a
bit better compromise than the previous tricks being used. Still not
perfect, but perhaps less likely to fail for the freebsd build.

Cheers, Tridge