classes/lib: Remove bb.build.FuncFailed

classes/lib: Remove bb.build.FuncFailed

Whilst seemingly a good idea, this exception doesn't really serve any purpose
that bb.fatal() doesn't cover. Wrapping exceptions within exceptions isn't
pythonic.

Its not used in many places, lets clean up those and remove usage of it
entirely. It may ultimately be dropped form bitbake entirely.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>