Concepts: Create space for requires-clause in TemplateParameterList; NFC
Space for storing the constraint-expression of the
requires-clause associated with a TemplateParameterList is
arranged by taking a bit out of the NumParams field for the purpose
of determining whether there is a requires-clause or not, and by
adding to the trailing objects tied to the TemplateParameterList. An
accessor is provided.
An appropriate argument is supplied to TemplateParameterList::Create
at the various call sites.
Serialization changes will addressed as the Concepts implementation
becomes more solid.
This change also replaces the custom
FixedSizeTemplateParameterListStorage implementation with one that
follows the interface provided by llvm::TrailingObjects.
Reviewers: aaron.ballman, faisalv, rsmith
Subscribers: cfe-commits, nwilson
Differential Revision: https://reviews.llvm.org/D19322