Not sure why this is the case, but maybe something to do with it not testing for cpu optimization flags correctly. At any rate this is the only way it will build. Other folks have reproduced the same problem by removing the mmx, sse, and sse2 USE flags and it will fail to build. Reproducible: Always Steps to Reproduce: 1.remove mmx, sse, sse2 USE flags 2.emerge mplayer 3. Not a major problem, but could be for someone who does not have mmx, sse and sse2 in their USE flags.
*** This bug has been marked as a duplicate of bug 156375 ***