cleanup: clarify disabling of static assert checks

[nurupo]

Since we have now switched to C11 for all compilers but MSVC.

(tox-bootstrapd is Unix-only while MSVC is Windows-only, so MSVC using C99 is not an issue as it never builds tox-bootstrapd).

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (65b3375) 74.39% compared to head (63fb294) 74.41%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2451      +/-   ##
==========================================
+ Coverage   74.39%   74.41%   +0.02%     
==========================================
  Files          87       87              
  Lines       26264    26264              
==========================================
+ Hits        19539    19545       +6     
+ Misses       6725     6719       -6     

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[nurupo]

Those clang-tidy checks failing seem like false positives, because const int can't be used in static_assert() in C. clang-tidy is probably thinking of C++.

Anyway, changing this turned out to be rather annoying:

1. cont int is not a constant expression in C and doesn't work with static_assert():

   error: static_assert expression is not an integral constant expression
   

2. enum {foo = a, bar = b} doesn't work because we use the enums in a comparison:

   ./other/bootstrap_daemon/src/tox-bootstrapd.c:491:70: error: enumerated and non-enumerated type in conditional expression [-Werror=extra]
     491 |                     limit.rlim_cur = limit.rlim_max > RLIM_SUGGESTED ? RLIM_SUGGESTED : limit.rlim_max;
         |                                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   

3. define it is then.

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The whole point of the assert is to hint to the reader that the rest of the code was written under the assumption that rlim_suggested >= rlim_min so you should keep that property if you are going to modify the values of the constants. It's nice for it to get checked at compile-time in case someone edited without getting the hint.

[nurupo]

Or should we just keep the code as it is with the clang-tidy checks disabled?

[iphydf]

Yes, disable the useless check.

[iphydf]

Looks good. Disable the checks with a brief explanation in the script.