niti: add method `NaiveInterpreter.callsite` to prepare complex callsite

This will enable the extension of the behavior, especially for new init.

Signed-off-by: Jean Privat <jean@pryen.org>
auto_super_init: clean signature check

use local variables to improve code

Signed-off-by: Jean Privat <jean@pryen.org>
auto_super_init: use CallSite

this will simplify calls on (future) new-style init since the logic
will be in the CallSite part.

Signed-off-by: Jean Privat <jean@pryen.org>
lib/hashcol: forgot to nullify a link in `HashCollection::enlarge`

Thus caused buggy bucklet-link update in `HashSet::remove`
Thus caused buggy transitive reduction in `POSet::add_edge`
Thus caused buggy coloration in `layout_builders`
Thus caused buggy type test tables in `SeparateCompiler::compile_type_to_c`
Thus caused buggy type tests in programs

Fixes #307
Signed-off-by: Jean Privat <jean@pryen.org>
Merge branch 'fix_hashcol_enlarge'
Merge branch 'callsite'

Annother short clean-n-prepare series for the new inits