Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20160611' into staging

Merge remote-tracking branch 'remotes/rth/tags/pull-tcg-20160611' into staging

TB hashing improvements

# gpg: Signature made Sun 12 Jun 2016 01:12:50 BST
# gpg:                using RSA key 0xAD1270CC4DD0279B
# gpg: Good signature from "Richard Henderson <rth7680@gmail.com>"
# gpg:                 aka "Richard Henderson <rth@redhat.com>"
# gpg:                 aka "Richard Henderson <rth@twiddle.net>"
# Primary key fingerprint: 9CB1 8DDA F8E8 49AD 2AFC  16A4 AD12 70CC 4DD0 279B

* remotes/rth/tags/pull-tcg-20160611:
  translate-all: add tb hash bucket info to 'info jit' dump
  tb hash: track translated blocks with qht
  qht: add test-qht-par to invoke qht-bench from 'check' target
  qht: add qht-bench, a performance benchmark
  qht: add test program
  qht: QEMU's fast, resizable and scalable Hash Table
  qdist: add test program
  qdist: add module to represent frequency distributions of data
  tb hash: hash phys_pc, pc, and flags with xxhash
  exec: add tb_hash_func5, derived from xxhash
  qemu-thread: add simple test-and-set spinlock
  include/processor.h: define cpu_relax()
  seqlock: rename write_lock/unlock to write_begin/end
  seqlock: remove optional mutex
  compiler.h: add QEMU_ALIGNED() to enforce struct alignment

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