MS ABI x64: Don't destroy arguments twice on x64

We were destroying them in the callee, and then again in the caller.  We
should use an EH-only cleanup and disable it at the point of the call
for win64, even though we don't use inalloca.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@207733 91177308-0d34-0410-b5e6-96231b3b80d8
Add support for __declspec(thread) under -fms-extensions

Reviewers: rsmith

Differential Revision: http://reviews.llvm.org/D3551

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@207734 91177308-0d34-0410-b5e6-96231b3b80d8
Avoid a potential race between stat() and open() of ASTFile

We need to open an ASTFile while checking its expected size and
modification time, or another clang instance can modify the file between
the stat() and the open().

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@207735 91177308-0d34-0410-b5e6-96231b3b80d8