lib/wp/meson.build: make gnome.generate_gir optional
Hello,
Since wireplumber became a part of AGL project, the build process for community board "HSDK"(ARC processor) started to fail on the step of generation introspection data(GIR). Currently there is no available qemu port for ARC, so we are disabling GIR in yocto, see: https://www.yoctoproject.org/docs/2.3.2/dev-manual/dev-manual.html#disabling-the-generation-of-introspection-data
In some packages, like json-glib, there is a check before GIR generation, if it is enabled or not: https://gitlab.gnome.org/GNOME/json-glib/blob/master/json-glib/meson.build#L96
In current version of wireplumber the generation of GIR in lib/wp/meson.build occurs without any checks, which leads to error for out board. Could you please add configure option, like "-disable-introspection", depending on which GIR would(or not) be generated.