runtime/race package contains the data race detector runtime library.
It is based on ThreadSanitizer race detector, that is currently a part of
the LLVM project (http://llvm.org/git/compiler-rt.git).
To update the .syso files use golang.org/x/build/cmd/racebuild.
Current runtime is built on rev 389d49d4943780efbfcd2a434f4462b6d0f23c44.