meta-openpli: libungif not needed any more, use giflib from OE

Switch to OE giflib witch is API and ABI compatible with libungif. Thanks blzr!

Signed-off-by: Mike Looijmans <milo-software@users.sourceforge.net>
Merge branch 'master' of git://git.code.sf.net/p/openpli/openpli-oe-core