clang-format: Add spaces between lambdas and comments.

Before:
  void f() {
    bar([]() {}// Does not respect SpacesBeforeTrailingComments
        );
  }

After:
  void f() {
    bar([]() {} // Does not respect SpacesBeforeTrailingComments
        );
  }

This fixes llvm.org/PR19017.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@203466 91177308-0d34-0410-b5e6-96231b3b80d8