Merge remote-tracking branch 'remotes/rth/tags/pull-hppa-20180204' into staging

hppa-softmmu update

# gpg: Signature made Sun 04 Feb 2018 22:20:40 GMT
# gpg:                using RSA key 64DF38E8AF7E215F
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>"
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth/tags/pull-hppa-20180204:
  roms/seabios-hppa: Update submodule and image
  tests: Enable boot-serial-test for hppa
  hw/hppa: Use qemu_log_mask instead of fprintf to stderr

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>