[sanitizer] Fix the return type for GetTid in Fuchsia implementation
[sanitizer] Fix the return type for GetTid in Fuchsia implementation

This is triggering "functions that differ only in their return type
cannot be overloaded" error.

Differential Revision: https://reviews.llvm.org/D44126

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@326759 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