xray: Add missing header to list of installed headers.
xray: Add missing header to list of installed headers.

Spotted by gn's llvm/utils/gn/build/sync_source_lists_from_cmake.py script.

Differential Revision: https://reviews.llvm.org/D56797

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@351479 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt