and update is_null_expr and is_non_null_expr in a similar manner as the other ones

The name seems to imply that it will return Some for any constant integer expression,
not only for integer literals

A fixe for Git versions < 2.22

See merge request frama-c/frama-c!3892

Improve support for functions returning structures

See merge request frama-c/frama-c!3891

Feature/thibaut/type recursive predicates

See merge request frama-c/frama-c!3759

Fix test checking wildcard rules of ACSL parser

See merge request frama-c/frama-c!3878

[distrib] improve distrib script - headers handling

Closes #594 and #506

See merge request frama-c/frama-c!3881

[devman] fix visitor example following SO question

See merge request frama-c/frama-c!3882

See https://stackoverflow.com/questions/73094227/how-do-i-declare-a-logic-variable

- check headers before changing them
- fail to build open-source distrib with close source file

[Makefile] install share/Makefile.common

See merge request frama-c/frama-c!3880

[ptests] allows %{read:file} in STDOPT/OPT/EXECNOW

See merge request frama-c/frama-c!3879

[wp] new solver stats

See merge request frama-c/frama-c!3840