[expr.prim.req] Editorial wording change.
[expr.prim.req] Factor "always fail" conditions out of
specific constraints.
[expr.prim.req] Update example.
[expr.prim.req] Reworking example.
[expr.prim.req] Remove unnecessary wording.
Merge branch 'master' of https://github.com/cplusplus/concepts-ts
[dcl.spec.auto] Remove note about auto in non-deduced context.