Set Bullet Behavior "Strict Subproofs".
Definition extlink := ext_link_prog prog.
Definition Espec := add_funspecs (Concurrent_Espec unit _ extlink) extlink Gprog.
Existing Instance Espec.

(* This lemma ties all the function proofs into a single proof for the entire program. *)
Lemma all_funcs_correct:
semax_func Vprog Gprog (prog_funct prog) Gprog.