[LTO] Move UpdateCompilerUsed.h from lib/ to include/

I plan to use it in lld soon.

Differential Revision:  http://reviews.llvm.org/D21575


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273380 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed