Fix libxml_get_last_error() signature

[simPod]

No description provided.

[codecov]

Codecov Report

Merging #155 into master will not change coverage by %.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #155   +/-   ##
=========================================
  Coverage     85.18%   85.18%           
  Complexity     9667     9667           
=========================================
  Files           541      541           
  Lines         24439    24439           
=========================================
  Hits          20819    20819           
  Misses         3620     3620           

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[ondrejmirtes]

The same thing is one line above in libxml_get_errors. Please fix that too (and in the rest of the file if you find it too).

[ondrejmirtes]

Thank you!