Fix unused-lambda-capture warning by using default capture-by-ref
Fix unused-lambda-capture warning by using default capture-by-ref

Since the lambda isn't escaped (via a std::function or similar) it's
fine/better to use default capture-by-ref to provide semantics similar
to language-level nested scopes (if/for/while/etc).

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@311782 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 7cd5c4385447a19aaaec38b24cdb48183ca69570)

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm