glcpp: Simplify calling convention of parser's active_list functions

glcpp: Simplify calling convention of parser's active_list functions

These were all written as generic list functions, (accepting and returning
a list to act upon). But they were only ever used with parser->active as
the list. By simply accepting the parser itself, these functions can update
parser->active and now return nothing at all. This makes the code a bit
more compact.

And hopefully the code is no less readable since the functions are also
now renamed to have "_parser_active" in the name for better correlation
with nearby tests of the parser->active field.