Simplify memory management of CXEvalResultKind/ExprEvalResult using unique_ptr and a dtor
Simplify memory management of CXEvalResultKind/ExprEvalResult using unique_ptr and a dtor

This doesn't seem to need to be a C type, C only handles a void*, so use
new/delete as usual to simplify allocation and cleanup.

Follow-up to r265994

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@266222 91177308-0d34-0410-b5e6-96231b3b80d8

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