[dsymutil] Replace TimeValue with TimePoint

Summary:
All changes are pretty straight-forward. I chose to use TimePoints with
second precision, as that is all that seems to be required here.

Reviewers: friss, zturner

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25908

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286358 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed