Problem: hard to track usage of CCACHE in Jenkins builds
Problem: hard to track usage of CCACHE in Jenkins builds

Solution: add an option to keep a CCACHE_LOGFILE for postmortems in a workspace (off by default)

Signed-off-by: Jim Klimov <161274d284b04ac67a00ff578101b826c5a5ca28@eaton.com>

zeromq/zproject,zeromq/zproject,zeromq/zproject