I would suggest moveing "tmp/portage/.distcc" up to "/tmp/.distcc". Why well heree is an ex: 177M in a crashed linux-headers emerge (this morning), about 500M in a X emerge crash. I normally "rm -r /tmp/portage/*" but there sits .distcc/lock state and barrel opps I mean .distcc. Ill copyem trashem and see what happens.
Huh? There is no reason to move distcc from /var/tmp/portage/.distcc However, if you like, you may define DISTCC_DIR in /etc/make.conf.