tsan: fix Go ppc64le build

This #define is in the non-Go ppc64le build but not in the Go build.

Reviewed-in: https://reviews.llvm.org/D68046
Author: randall77 (Keith Randall)



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@374868 91177308-0d34-0410-b5e6-96231b3b80d8