Allow building with either giflib 4.2 or 5.0


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@375632 35697150-7ecd-e111-bb59-0022644237b5
Allow building with either giflib 4.2 or 5.0


git-svn-id: svn+ssh://svn.freebsd.org/ports/head@375636 35697150-7ecd-e111-bb59-0022644237b5