[ccache] Build failure

[Andrew Stubbs]

Unless I'm missing something, the ccache sources are currently not 
buildable. :-(

ccache.c: In function ‘put_file_in_cache’:
ccache.c:808:42: error: ‘struct conf’ has no member named ‘compress_level’
     source, dest, conf->compression ? conf->compress_level : 0);
                                           ^
Andrew