Patch 4 and 5 of 7, improve PPC HW capabiltiy checking.

Patch 4 and 5 of 7, improve PPC HW capabiltiy checking.

The patch was submitted by Will Schmidt  (will_schmidt@vnet.ibm.com).

Patches 4 and 5 need to be applied together.  Add convenience function
for processing hwcap entries. Add logic to check for HTM support in compiler.

Bugzilla 34979

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15423