Merge tag 'ppc-for-2.7-20161013' into stable-2.7-staging

qemu-2.7 (stable): ppc patch queue 2016-10-13

TCG for ppc does not properly implement hardware transactional memory.
It has a stub implementation in which transactions always fail.
Unfortunately in v2.7.0, HTM is advertised as being available to
guests, which means guests may incorrectly attempt to use it and hang.

This has been the case for a while, but has become more urgent with
recent (guest) Linux kernel versions which attempt to lazily enable
TM.  Under TCG that now triggers the problem regularly, instead of
just when running a TM aware userspace program.

The problem is already fixed in the 2.8/master branch, by correctly
advertising HTM as not being available with TCG.  This series
backports the relevant patches to the qemu-2.7 stable branch to fix
the problem there.

* tag 'ppc-for-2.7-20161013':
  ppc: Check the availability of transactional memory
  hw/ppc/spapr: Fix the selection of the processor features
  hw/ppc/spapr: Move code related to "ibm,pa-features" to a separate function
  linux-headers: update