AST: improve layout of SimpleTypoCorrector
AST: improve layout of SimpleTypoCorrector

Add the "explicit" specifier to the single-argument constructor of
SimpleTypoCorrector.  Reorder the fields to remove excessive padding (8 bytes).

Patch by Alexander Shaposhnikov!

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@279946 91177308-0d34-0410-b5e6-96231b3b80d8

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