libfprint/tod/build: Require libgusb dependency on pkgconfig

We include the directories so we definitely need to depend on it at
compile time.

libfprint/tod/meson.build

@@ -70,6 +70,7 @@ pkgconfig.generate(libfprint_tod,
     subdirs: tod_subpath,
     requires_private: [
         versioned_libname,
+        gusb_dep,
     ],
     variables: [
         'tod_driversdir=${libdir}/@0@'.format(tod_subpath)