Code quality issue in SHA3: useless division

[msprotz]

Reported by @karthikbhargavan

https://github.com/hacl-star/hacl-star/blob/main/dist/gcc-compatible/Hacl_Hash_SHA3.c#L307 could be 1 instead of a division

[R1kM]

Permanent link for the code mentioned above:

hacl-star/dist/gcc-compatible/Hacl_Hash_SHA3.c

Line 307 in 8bc5b21

Hacl_Hash_SHA3_update_multi_sha3(a1, s2, buf, block_len(i) / block_len(a1));

[R1kM]

Relevant F* code:
The call to update_multi in the generic functor implementation:

hacl-star/code/streaming/Hacl.Streaming.Functor.fst

Line 1361 in 90a3b50

c.update_multi (G.hide i) block_state prevlen buf (c.blocks_state_len i);

The update_multi instantiation for Keccak:

hacl-star/code/streaming/Hacl.Streaming.Keccak.fst

Line 177 in 37f0d97

Hacl.Hash.SHA3.update_multi a s () blocks (len `U32.div` Hacl.Hash.SHA3.(block_len a)))