Headers: be a bit more careful about inline asm
Headers: be a bit more careful about inline asm

Conditionally include x86intrin.h if we are building for x86 or x86_64.
Conditionalise definition of inline assembly routines which use x86 or x86_64
inline assembly. This is needed as clang can target Windows on ARM where these
definitions may be included into user code.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@211716 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang