graphics/linux-c6-gdk-pixbuf: rename to -pixbuf2

- Rename gdk-pixbuf to linux-c6-gdk-pixbuf2 to properly distinguish between
  linux- gdk-pixbuf 1 and 2.
- Change consumers dependencies to match.

PR: 		195120, 195121
Differential Revision:	https://reviews.freebsd.org/D1192
Submitted by:	Jan Beich <jbeich@vfemail.net>
Reviewed by:	rene (emulation)
Approved by:	swills (mentor)
Approved by:	portmgr (swills)


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@373192 35697150-7ecd-e111-bb59-0022644237b5