message: ci: Print ccache statistics summary
diff: export LC_ALL=C.UTF-8
  BITCOIN_CONFIG_ALL="--disable-dependency-tracking --prefix=$DEPENDS_DIR/$HOST --bindir=$BASE_OUTDIR/bin --libdir=$BASE_OUTDIR/lib"
  +DOCKER_EXEC "command -v ccache > /dev/null && ccache --zero-stats"
  if [ -z "$NO_DEPENDS" ]; then
  DOCKER_EXEC ccache --max-size=$CCACHE_SIZE
  fi
  @@ -44,3 +45,7 @@ trap 'DOCKER_EXEC "cat ${BASE_SCRATCH_DIR}/sanitizer-output/* 2> /dev/null"' ERR
  BEGIN_FOLD build
  DOCKER_EXEC make $MAKEJOBS $GOAL || ( echo "Build failure. Verbose build follows." && DOCKER_EXEC make $GOAL V=1 ; false )
  END_FOLD
  +
  +BEGIN_FOLD ccache_stats
  +DOCKER_EXEC "command -v ccache > /dev/null && ccache --version | head -n 1 && ccache --show-stats"
  +END_FOLD
  