Reflow this comment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215160 91177308-0d34-0410-b5e6-96231b3b80d8
Add a separate testcase for a DWARF expression describing a value in a
subregister.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215161 91177308-0d34-0410-b5e6-96231b3b80d8