meson: prevent RPATH stripping

meson: prevent RPATH stripping

By default, Meson strips RPATH from the executable it builds [1,2],
unless explicitly set via install_rpath.

This will make support/scripts/check-host-rpath fail when building the
host variant of a Meson-based package.

So add a patch to prevent RPATH from being stripped if install_rpath is
not set and notify user about it.

[1] https://github.com/mesonbuild/meson/issues/2567
[2] https://github.com/mesonbuild/meson/issues/314#issuecomment-157658562

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>