fix cmake code for cross-build usage.
Initial directive "command KF5::desktoptojson ..." points
the target's arch desktoptojson binary instead of the host's one.

--- a/KF5CoreAddonsMacros.cmake	2022-02-05 22:20:29.000000000 +0100
+++ -	2022-02-13 23:13:24.523896883 +0100
@@ -46,7 +46,8 @@
         return()
     endif()
     kcoreaddons_desktop_to_json_crosscompilation_args(_crosscompile_args)
-    set(command KF5::desktoptojson ${_crosscompile_args} -i ${desktop} -o ${json})
+    get_target_property(DESKTOPTOJSON_LOCATION KF5::desktoptojson LOCATION)
+    set(command ${DESKTOPTOJSON_LOCATION} -i ${desktop} -o ${json})
     if(DESKTOP_TO_JSON_COMPAT_MODE)
       list(APPEND command -c)
     endif()
