[TSan] Update test values
[TSan] Update test values

Summary:
This test was broken by the tail duplication logic being changed in
r311139, update the test values and add a note about how to properly run
a benchmark to verify that the values are safe to update.

Reviewers: vitalybuka

Reviewed By: vitalybuka

Subscribers: dvyukov, kubamracek

Differential Revision: https://reviews.llvm.org/D36889

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@311189 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