MS ABI: Return sret parameters when using inalloca

Previously the X86 backend would look for the sret attribute and handle
this for us.  inalloca takes that all away, so we have to do the return
ourselves now.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202097 91177308-0d34-0410-b5e6-96231b3b80d8
IRGen: Simplify alignment calculation in setBitFieldInfo

Take advantage of CharUnits::alignmentAtOffset instead of calculating it
by hand.

Differential Revision: http://llvm-reviews.chandlerc.com/D2862


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202098 91177308-0d34-0410-b5e6-96231b3b80d8
AST: Simplify CharUnits::alignmentAtOffset

CharUnits::alignmentAtOffset is equivalent to llvm::MinAlign but
slightly less efficient.  Use it's implementation instead.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202099 91177308-0d34-0410-b5e6-96231b3b80d8