Merge remote-tracking branch 'remotes/riscv/tags/riscv-for-master-3.1-rc2' into staging

RISC-V Patches for 3.1-rc2

This pull request contains four patches that aren't really related to
each other aside from all being bug fixes that I think should go in for
3.1.0:

* The second half of Alistair's memory leak patch set that I missed last
  week.
* A fix to make fclass.d availiable only on RV64IFD systems (without
  this it's availiable on RV32IFD systems, truncating the result).
* A fix to make sfence.vm availiable only in priv-1.9.1, and sfence.vma
  only availiable in priv-1.10.
* A change to respect fences in user-mode emulators, which were
  previously treated as NOPs.

As usual, this builds and boot Linux for me.  I don't think I have
anything else planned for 3.1.0, but I may be wrong as things are a bit
hectic this week.

# gpg: Signature made Tue 13 Nov 2018 23:48:38 GMT
# gpg:                using RSA key EF4CA1502CCBAB41
# gpg: Good signature from "Palmer Dabbelt <palmer@dabbelt.com>"
# gpg:                 aka "Palmer Dabbelt <palmer@sifive.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 00CE 76D1 8349 60DF CE88  6DF8 EF4C A150 2CCB AB41

* remotes/riscv/tags/riscv-for-master-3.1-rc2:
  RISC-V: Respect fences for user-only emulators
  target/riscv: Fix sfence.vm/a both available in any priv version
  target/riscv: Fix FCLASS_D being treated as RV64 only
  hw/riscv/virt: Free the test device tree node name

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