For gtk3. Change to single include instead of including individual headers.

git-svn-id: https://xchat.svn.sourceforge.net/svnroot/xchat@1522 893a96be-7f27-4fdf-9d1e-6aeec9d3cce1
Fix the check for argument count in hook_fd.

git-svn-id: https://xchat.svn.sourceforge.net/svnroot/xchat@1523 893a96be-7f27-4fdf-9d1e-6aeec9d3cce1