Minor cleanup.

DS parameter  has a default (null) value anyway, so there's no need for an
if/else here.
Patch by Nikola Smiljanić.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171210 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed