Add definitions for "armv6m", which indicates a Cortex-M0 processor.
It uses the T16 and a few T32 instructions from the ARMv7-A ISA.
<rdar://problem/15099306> 


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@191587 91177308-0d34-0410-b5e6-96231b3b80d8