Remove unroll pragma metadata after it is used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213412 91177308-0d34-0410-b5e6-96231b3b80d8
Fix build breakage introduced with r213412.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213414 91177308-0d34-0410-b5e6-96231b3b80d8