Make setABIAPCS and setABIAAPCS easier to reason about.
Make setABIAPCS and setABIAAPCS easier to reason about.

These functions now always set the same variables in the same order and they
don't overlap with thep constructor.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@197604 91177308-0d34-0410-b5e6-96231b3b80d8

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