[ccache] ccache 2.2.1

[tridge at samba.org]

I released ccache 2.0 a couple of days ago, and have done two minor
releases since then to fix small bugs that were noticed in the 2.0
release.

Main changes are:

 - minor Makefile install fixes
 - fixed some compilation warnings
 - added -C option for 'clear cache completely'
 - added CCACHE_CC option
 - added CCACHE_RECACHE option
 - added CCACHE_EXTENSION option
 - added CCACHE_HASHDIR option
 - embed the hostname in temporary file names for NFS sharing
 - better handling of the various -M compiler options
 - handle attempts to compile to stdout
 - set default max cache size to 1GB
 - better signal handling

Cheers, Tridge