cleanup: Allocate logger using tox memory allocator.

[iphydf]

This change is 

[codecov]

Codecov Report

Attention: Patch coverage is 86.95652% with 3 lines in your changes missing coverage. Please review.

Project coverage is 73.15%. Comparing base (fa723e3) to head (4ac569b).
Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
toxcore/logger.c	77.77%	2 Missing ⚠️
toxcore/forwarding_fuzz_test.cc	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2789      +/-   ##
==========================================
+ Coverage   72.96%   73.15%   +0.18%     
==========================================
  Files         149      149              
  Lines       30566    30566              
==========================================
+ Hits        22303    22360      +57     
+ Misses       8263     8206      -57     

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