lib/static-delta: Drop duplicated declaration from private header
lib/static-delta: Drop duplicated declaration from private header

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Closes: #1347
Approved by: cgwalters

GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree,GNOME/ostree