cleanup: Use tox memory allocator in some more places.

[iphydf]

This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 96.96970% with 2 lines in your changes missing coverage. Please review.

Project coverage is 72.38%. Comparing base (958d91e) to head (025177a).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
toxcore/friend_connection.c	85.71%	1 Missing ⚠️
toxcore/friend_requests.c	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2829      +/-   ##
==========================================
- Coverage   72.63%   72.38%   -0.25%     
==========================================
  Files         150      150              
  Lines       30757    30798      +41     
==========================================
- Hits        22339    22293      -46     
- Misses       8418     8505      +87     

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