chore(xutil): clear compile warnings

[cnjhb]

warning: '__builtin_memcpy' specified bound between 18446744071562067968 and 18446744073709551615 exceeds maximum object size 9223372036854775807 [-Wstringop-overflow=]
29 | return __builtin___memcpy_chk (__dest, __src, __len,

The length parameter in memcpy cannot be negative.

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.47%. Comparing base (94d38e6) to head (1518f90).
⚠️ Report is 10 commits behind head on master.

Files with missing lines	Patch %	Lines
common/xutil.h	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4087      +/-   ##
==========================================
+ Coverage   90.45%   90.47%   +0.01%     
==========================================
  Files         941      941              
  Lines       60385    60386       +1     
  Branches     1145     1146       +1     
==========================================
+ Hits        54621    54633      +12     
+ Misses       5254     5245       -9     
+ Partials      510      508       -2     

Files with missing lines	Coverage Δ
common/xutil.h	86.66% <83.33%> (-6.67%)	⬇️

... and 3 files with indirect coverage changes

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[actionless]

thanks again!