remove unnecessary let #81

Job	Run time
closure	11m 7s
closure_cfg	8m 23s
flambda1	9m 39s
flambda1_frame_pointers	9m 13s
flambda1_cfg	8m 19s
flambda2_debug_runtime	12m 53s
flambda2_debug_runtime_nnp	14m 3s
flambda2_nnp_o3	10m 58s
flambda2_frame_pointers_oclassic	10m 41s
flambda2_cfg	11m 18s
flambda2_macos	9m 14s
irc	9m 22s
irc_frame_pointers	9m 23s
ls	9m 39s
build_upstream_closure	13m 34s
	2h 37m 46s

Provide feedback