build: Add missing argument to the introspection scanner
build: Add missing argument to the introspection scanner

The autotools build specifies the include header with the --c-include
argument for g-ir-scanner, so we need to do the same when building with
Meson.

GNOME/json-glib,ebassi/json-glib,GNOME/json-glib,ebassi/json-glib,frida/json-glib,frida/json-glib,ebassi/json-glib