ReadSourceManagerBlock is skipping over records that can contain Blobs.  Not passing
in a StringRef to bind to them forces them to be unpacked into the Record as individual
bytes.  This is wasteful, but not likely to be measurable in this instance.
[analyzer] Show notes inside implicit calls at the last explicit call site.

Before:
  struct Wrapper { <-- 2. Calling default constructor for 'NonTrivial'.
    NonTrivial m;
  };

  Wrapper w; <-- 1. Calling implicit default constructor for 'Wrapper'.

After:
  struct Wrapper {
    NonTrivial m;
  };

  Wrapper w; <-- 1. Calling implicit default constructor for 'Wrapper'.
             ^-- 2. Calling default constructor for 'NonTrivial'.