libnewt: Backport patch to fix reproducibility

Backports a patch from upstream to fix a reproducibility problem where
paths would be encoded in the binary.

Drops an obsolete patch that conflicted with the backport

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>