[clang] Add cc1 option for dumping layout for all complete types

This change adds an option which, in addition to dumping the record
layout as is done by -fdump-record-layouts, causes us to compute the
layout for all complete record types (rather than the as-needed basis
which is usually done by clang), so that we will dump them as well.
This is useful if we are looking for layout differences across large
code bases without needing to instantiate every type we are interested in.

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D104484