The ebuild in summary is currently forcing users to use serial make (-j1, no extra job tasks). This seems not to be needed. The ebuild was modified to use -j8 on a truly 8-core SMP system and didn't fail the build, you should either check if it's a particular USE flag to cause the problem, or drop -j1 and leave the user to decide how many jobs to use. I want to remember you that with modern multicore systems, forcing serial make is going to waste a lot of time and resources for users.. Thanks, Diego
Fixed in dev-libs/icu-4.0.1.