[SECP256K1] WNAF of lambda_split output has max size 129
[SECP256K1] WNAF of lambda_split output has max size 129

Summary:
Partial backport 9/11 of secp256k1 [[https://github.com/bitcoin-core/secp256k1/pull/830 | PR830]]:
https://github.com/bitcoin-core/secp256k1/pull/830/commits/2edc514c90293af8f602e4376e832773779c9426

Depends on D8044.

Test Plan:
  ninja check-secp256k1

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D8045

Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc,Bitcoin-ABC/bitcoin-abc