package/pkg-meson.mk: fix deprecation warnings in cross-compilation.conf

package/pkg-meson.mk: fix deprecation warnings in cross-compilation.conf

As of meson 0.56.0, `<lang>_args` and `<lang>_link_args` in the
`[properties]` section are deprecated and should be placed in the
`[built-in options]` section instead.

Source: https://mesonbuild.com/Machine-files.html#properties

Fixes the following deprecation warnings:

> DEPRECATION: c_args in the [properties] section of the machine file is deprecated, use the [built-in options] section.
> DEPRECATION: c_link_args in the [properties] section of the machine file is deprecated, use the [built-in options] section.
> DEPRECATION: cpp_args in the [properties] section of the machine file is deprecated, use the [built-in options] section.
> DEPRECATION: cpp_link_args in the [properties] section of the machine file is deprecated, use the [built-in options] section.

Signed-off-by: Gleb Mazovetskiy <glex.spb@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>