Gentoo's Bugzilla –
Attachment 596990 Details for
Bug 700838x11-base/xorg-server-1.20.5 - ld: os-support/.libs/libxorgos.a(sigio.o): in function `xf86InstallSIGIOHandler': .../work/xorg-server-1.20.5/hw/xfree86/os-support/linux/./../shared/sigio.c:212: undefined reference to `isastream'