[ARM] Support for ARMv6-Z / ARMv6-ZK missing

As Richard Barton observed at http://reviews.llvm.org/D12937#inline-107121
TargetParser in LLVM has insufficient support for ARMv6Z and ARMv6ZK.

In particular, there were no tests for TrustZone being supported in these
architectures.

The patch clears a FIXME: left by Saleem Abdulrasool in r201471, and fixes
his test case which hadn't really been testing what it was claiming to test.

Differential Revision: http://reviews.llvm.org/D13236

llvm-svn: 248921