[ARM] Pass thumb as architecture to the underlying tools, when targeting windows

This makes sure that the thumb section flag gets set by the assembler.

Patch by Martin Storsjö.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@276869 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed