app-emulation/qemu: need seavgabios for pseries

app-emulation/qemu: need seavgabios for pseries

Emulation of PPC64 pSeries needs a VGA BIOS:
$ qemu-system-ppc64 -m 256 -nographic \
  -echr 0x05 \
  -kernel cirros-0.4.0~pre1-ppc64-kernel \
  -initrd cirros-0.4.0~pre1-ppc64-initramfs \
  -append rdroot \
  -m 256 \
  -machine pseries
qemu-system-ppc64: Initialization of device VGA failed: failed to find romfile "vgabios-stdvga.bin"

Tested on bogsucker.ppc64.dev.g.o by booting CirrOS PPC64 images.

Package-Manager: Portage-2.3.8, Repoman-2.3.3
Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>