[asan] inline PoisonShadow in FakeStack to get ~10% speedup

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@190660 91177308-0d34-0410-b5e6-96231b3b80d8
[asan] use TLS on Linux to get the FakeStack. Saves 15% performance

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@190661 91177308-0d34-0410-b5e6-96231b3b80d8
[asan] undo the previous commit since TLS hack breaks with signals... :(

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@190662 91177308-0d34-0410-b5e6-96231b3b80d8
[asan] second attempt to use TLS with fake stack. This time it looks (more) async-signal safe.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@190663 91177308-0d34-0410-b5e6-96231b3b80d8