Cross-platform support and a workaround for consult chars outside unicode in native module

[sashimacs]

I have a couple minor changes suggested in this PR:

• *u8 string literals are not available in C99 (cpp references says since C11), so bumped C_STANDARD
• sysinfo / get_nprocs() is unavailable on macOS so I'm using sysconf to get processor count.
• Added hotfuzz--fix-tofu-chars to add as advice on native filtering to fix issues with consult-multi tofu characters outside unicode range, e.g. Getting hotfuzz-module to play nicely with consult #12, used like:

(advice-add 'hotfuzz--filter-c :around #'hotfuzz--fix-tofu-chars)

The consult workaround has some helper functions from https://github.com/magnars/dash.el which I pulled in to avoid having a whole dependency on dash, but can also refactor them and add a dependency if you think it's worth it.

[jwr]

FWIW, this advice-add fixed the breakage with consult for me nicely. It seems it wasn't pulled into the main hotfuzz codebase, though.

[codecov]

Codecov Report

Attention: Patch coverage is 59.09091% with 9 lines in your changes missing coverage. Please review.

Project coverage is 85.85%. Comparing base (6223294) to head (9b1cac9).

Files	Patch %	Lines
hotfuzz.el	59.09%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
- Coverage   93.50%   85.85%   -7.65%     
==========================================
  Files           1        1              
  Lines          77       99      +22     
==========================================
+ Hits           72       85      +13     
- Misses          5       14       +9     

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