Glib::ParseXSDoc

[Scott Lanning <lannings who int>]

I didn't find it in TODO, so I thought I'd mention
that the parse_file method doesn't take the 'INCLUDE:'
keyword (`perldoc perlxs`) into account. (The "non-piping"
include probably wouldn't be hard to implement, at least,
as long as care was taken regarding the MODULE line.)
I guess strictly speaking, since the doc says
"Parse one xs file." it's not a bug, but parsing
one xs file generally can involve an INCLUDE keyword.
I can implement this, but my interests are elsewhere
at the moment.