Only try to set the file permissions on regular files
Only try to set the file permissions on regular files

Fixes a build error with the mcomix package in openSUSE.

ximion/appstream-glib,ximion/appstream-glib,hughsie/appstream-glib,hughsie/appstream-glib,hughsie/appstream-glib,ximion/appstream-glib