I have a dual proc box, and use -j4. cutils gets into some sort of race condition with a parser file (yy.tab or parser.c or similar) when one build tries to move it as does another. Workaround (for now): edit make.conf just for this one use to -j1, then edit make.conf back to its normal settings after the emerge.
Hi W.A. I could not reproduce this, but I am not on an smp system either. Anyway I issued the -r1 ebuild that adds MAKEOPTS=-j1 before emake. Should do it for you. I also did few cleanups on the ebuild. Please test. George