On my hardened ~amd64 with gcc-4.8.0 I see a build failure for lilypond. The first error seems to be mf2pt1: "mpost -mem=mf2pt1 -progname=mpost '\mode:=localfont; mag:=100; bpppix 0.02; nonstopmode; input feta11.mf'" failed (No such file or directory) I manually checked and a file 'media-sound/lilypond-2.16.2/work/lilypond-2.16.2/mf/feta11.mf' does exist. On a note, this seems to be unrelated to gcc-4.8 since building with gcc-4.7 yields the same error.
Created attachment 346660 [details] media-sound:lilypond-2.16.2:20130426-181138.log.bz2
Created attachment 346662 [details] emerge --info
Seems to be gone with 2.18.