Refactor hashtable mpmc op set

[danielealbano]

The PR includes a refactor of the hashtable_mpmc_op_set function:

• a new function called hashtable_mpmc_op_set_update_value_if_key_exists has been extracted to update a value in the hashtable if the hash and the key are found and match, this is useful has the update code was being executed twce.
• refactor the function to use the extracted code

In addition the PR contains some very minor changes to fix the name of a support function and to improve some comments.

The main code changes will improve not only the readability but also the performances as less ICACHE will be occupied to run this code.

[codecov[bot]]

Codecov Report

Base: 82.93% // Head: 82.89% // Decreases project coverage by -0.03% :warning:

Coverage data is based on head (b91747e) compared to base (7727913). Patch coverage: 90.91% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #271 +/- ## ========================================== - Coverage 82.93% 82.89% -0.03% ========================================== Files 158 158 Lines 10251 10242 -9 ========================================== - Hits 8501 8490 -11 - Misses 1750 1752 +2 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `82.89% <90.91%> (-0.03%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano#carryforward-flags-in-the-pull-request-comment) to find out more. | [Impacted Files](https://codecov.io/gh/danielealbano/cachegrand/pull/271?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano) | Coverage Δ | | |---|---|---| | [...rc/data\_structures/hashtable\_mpmc/hashtable\_mpmc.c](https://codecov.io/gh/danielealbano/cachegrand/pull/271?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano#diff-c3JjL2RhdGFfc3RydWN0dXJlcy9oYXNodGFibGVfbXBtYy9oYXNodGFibGVfbXBtYy5j) | `94.74% <90.91%> (-0.78%)` | :arrow_down: | | [src/xalloc.c](https://codecov.io/gh/danielealbano/cachegrand/pull/271?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano#diff-c3JjL3hhbGxvYy5j) | `97.14% <0.00%> (+1.43%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Daniele+Salvatore+Albano)

:umbrella: View full report at Codecov.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.