parsing_cocci: visitor_ast0: Add attributefn to SmPL AST0 visitor
Add a public function for visiting attributes to the SmPL AST0 visitor. Add the AttributeTag constructor to AST0 and AST of SmPL.
In context_neg, add a few general fixes w/r/t the usage of the for_all2 function for comparing attributes.
Signed-off-by: Jaskaran Singh jaskaran.singh@collabora.com