package/execline: add option to build multicall binary
Since version 2.9.2.0, with another bugfix in 2.9.4.0, execline can
be built as a multicall binary, similar to busybox. According to
the author[1], this results in space savings of 66-87% on Linux.
[1]: https://skarnet.org/software/execline/execline.html
Signed-off-by: J. Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>