libproxy: update 0.4.18 -> 0.5.2

libproxy: update 0.4.18 -> 0.5.2

License-update: formatting, years

Upstream has completely overhauled the build system
(cmake -> meson) and available options. Add the most
important ones that require external dependencies;
there's plenty more if someone finds them useful.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>