cmake: remove .bbappends, resolved in oe-core

* it's included in daisy and master branches
  http://git.openembedded.org/openembedded-core/commit/?h=daisy&id=4f2dee0d8c2c3f60cb8f8021343e973cae31fc50

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>