Add a record with 2 fields : tnode and tattr

The builtins `__builtin_types_compatible_p` and `__builtin_va_arg` need
a type as argument. Frama-C converts them to an expression to be able to
type the builtin call.

This commit change the conversion in `cparser.mly` from a sizeof on the
type to a cast with a marker indicating from which builtin the argument
is coming from. This allows `cabs2cil` to type this expression
differently than a regular cast or sizeof.

also add `@since` and `@before` odoc tags

- Always print plugin except kernel
- The only optional plugin is used in extension_from and plugin_from
- All other acsl_extension functions take a plugin:string
  - these functions raise Not_found is the extension is not registered
  - can also fatal in case of ambiguity if plugin is None

- Plugins fields in the AST are used to find the right extension
- A plugin still cannot register twice an extension
- If plugin is not given, can throw ambiguity error
- Kernel extensions are an exception, a plugin cannot register an
extension with the name name than the kernel

- Cil_types.acsl_extension
- Logic_ptree.extension & global_extension

Loc will be updated once we encounter the definition

When using an enum in a ternary operator, the value is const-folded
before checking if it evaluates to `true` or `false` so that const-expr
used as enum values are supported.

David Bühler authored 6 months ago and Andre Maroneze committed 6 months ago

- uses the alignment of a field type instead of its size to compute
  the field alignement.
- removes incorrect special case for flexible array members, introduced to
  circumvent a crash when computing their size. As we now use the alignment
  instead of the size, the crash no longer occurs.
- merges the implementation of two similar cases (whether there are aligned
  field attributes or not).