core: Make mkdir -p function safer
core: Make mkdir -p function safer

Recursing here is just a more obvious way to do it, rather than
relying on the semantics of g_file_make_directory_with_parents().

gatispaeglis/ostree,sujitfulse/ostree,sujitfulse/ostree,resin-io/ostree,sujitfulse/ostree,leandrosansilva/ostree,sujitfulse/ostree,leandrosansilva/ostree,leandrosansilva/ostree,gatispaeglis/ostree,gatispaeglis/ostree,gatispaeglis/ostree,GNOME/ostree,resin-io/ostree,GNOME/ostree,resin-io/ostree,GNOME/ostree,leandrosansilva/ostree,gatispaeglis/ostree,sujitfulse/ostree,leandrosansilva/ostree,resin-io/ostree,gatispaeglis/ostree,GNOME/ostree,resin-io/ostree,GNOME/ostree