include: remove WARN_UNUSED_RESULT for functions always returning 1 #1659

1. 
   jonasnick commented at 9:37 am on March 13, 2025: contributor

   This makes the usage of the atribute consistent. In the musig and ellswift module, functions that return 1 always already don’t have the WARN_UNUSED_RESULT attribute. In secp256k1.h and the extrakeys module, this has only been the case partially.

   In all cases where this was removed, the function only returns 0 if the illegal callback has been called.

   Fixes #1379

2. include: remove WARN_UNUSED_RESULT for functions always returning 1

   This makes the usage of the atribute consistent. In the musig and ellswift
   module, functions that return 1 always already don't have the WARN_UNUSED_RESULT
   attribute. In secp256k1.h and the extrakeys module, this has only been the case
   partially.
   
   In all cases where this was removed, the function only returns 0 if the illegal
   callback has been called.

   1b6e081538
3. jonasnick added the label needs-changelog on Mar 13, 2025
4. real-or-random added the label assurance on Mar 13, 2025
5. real-or-random added the label refactor/smell on Mar 13, 2025
6. real-or-random approved
7. 
   real-or-random commented at 10:03 am on March 13, 2025: contributor

   utACK https://github.com/bitcoin-core/secp256k1/pull/1659/commits/1b6e081538cc9a171157ec858c4aac19deb7d6cc
8. 
   sipa commented at 12:15 pm on March 13, 2025: contributor

   utACK 1b6e081538cc9a171157ec858c4aac19deb7d6cc
9. real-or-random merged this on Mar 13, 2025
10. real-or-random closed this on Mar 13, 2025

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Contributors
jonasnick real-or-random sipa

Labels
assurance needs-changelog refactor/smell