* Fix unnecessary one-time recompile of stdlib with -enable-ossa-flag
This includes a bit in the module format to represent if the module was
compiled with -enable-ossa-modules flag. When compiling a client module
with -enable-ossa-modules flag, all dependent modules are checked for this bit,
if not on, recompilation is triggered with -enable-ossa-modules.
* Updated tests
Nothing besides static member refs on protocols feature is currently
using transitive protocols, so instead of trying to infer them on every
step let's do that only for base type of a dot-syntax reference when
there are no other bindings for it.
`PotentialBindings` lost most of its responsibilities,
and are no longer comparable. Their main purpose now
is binding and metadata tracking (introduction/retraction).
New `BindingSet` type is something that represents a set
of bindings at the current step of the solver.
