Note: formatc.lua was unable to swallow some newer additions to ExprASTNodeType
(specifically `kExprNodeOr = '|'` and probably something else), so all `= …`
were dropped: in any case they only were there in order to not bother updating
viml_pexpr_debug_print_ast_node and since it is now known all nodes which will
be present it is not much of an issue.
It also adds support for kExprLexOr which for some reason was forgotten.
It was only made sure that KLEE test compiles in non-KLEE mode, not that
something works or that KLEE is able to run tests.
