The problem (and solution) is the same as in http://bugs.gentoo.org/show_bug.cgi?id=218169#c11 and following Reproducible: Always
Um, so it's gentoo-sources that fails to produce a (working) kernel? If so, make the Summary reflect that, by putting the afflicted cat/pkg-version at the start of the line.
Quoting comment 11 from that bug: "The updated squash patch is nearly perfect. Just a #include <linux/sched.h> is missing in fs/squashfs/inode.c is missing. After including that line it compiles without errors and works without problems." Alex, first off thanks for the bug report (and the testing you've been doing). As Jeroen requested, in future it would help a lot if you could provide a short description and summary, even if it feels like you're duplicating stuff that's written elsewhere. Thanks... 5:)
Fixed and released in gentoo-sources-2.6.27-r1