bitbake.conf: Canonicalize paths in PSEUDO_IGNORE_PATHS

Use oe.path.canonicalize() to canonicalize the paths in
PSEUDO_IGNORE_PATHS before passing them to pseudo. This is needed since
pseudo will compare them to paths that are canonicalized.

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 1f2a497d)
Signed-off-by: Steve Sakoman <steve@sakoman.com>