[tsan] Include __tsan_external_* API from a header file instead of declaring them manually. NFC.

Differential Revision: https://reviews.llvm.org/D32384



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@301190 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed