[mips] '.set at=$0' should be equivalent to '.set noat'

Differential Revision: http://llvm-reviews.chandlerc.com/D3171

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204714 91177308-0d34-0410-b5e6-96231b3b80d8
[msan] More precise instrumentation of select IR.

Some bits of select result may be initialized even if select condition
is not.

https://code.google.com/p/memory-sanitizer/issues/detail?id=50


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204716 91177308-0d34-0410-b5e6-96231b3b80d8
Fix these tests on windows.

It is impossible to create a hard link to a non existing file, so create a
dummy file, create the link an delete the dummy file.

On windows one cannot remove the current directory, so chdir first.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204719 91177308-0d34-0410-b5e6-96231b3b80d8