tsan: allow fast large MemoryRangeSet on non-Windows Go
tsan: allow fast large MemoryRangeSet on non-Windows Go

The fast reset for large memory regions is not working
only on windows. So enable it for Go/linux/darwin/freebsd.

See https://github.com/golang/go/issues/20139
for background and motivation.

Based on idea by Josh Bleecher Snyder.



git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@301927 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