fix some warnings reported by llvm (see http://local.profusion.mobi:8081/~lfelipe...

fix some warnings reported by llvm (see local.profusion.mobi:8081/~lfelipe/output-efl/)

 * mainly unused parameters
 * in src/lib/imaging/evas_imaging.c, set font to NULL
 * in src/lib/canvas/evas_object_gradient.c, add unititialized member

there are a *lot* of reported warnings by llvm, i'll fix them later

there are also *lots* of unused parameters (compile evas with -W). I'll
fix them later too

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/evas@39172 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33