fix: remove redundant POSIX function aliases

[sergiud]

The preprocessor defines interfere with method declarations, e.g., in std::basic_filebuf, resulting in following error:

C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.37.32822\include\fstream(376,26): error C2039: '_close': is not a member of 'std::basic_filebuf<char,std::char_traits<char>>' [D:\a\glog\glog\build_Debug\logging_unittest.vcxproj]
C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.37.32822\include\iosfwd(244,35): message : see declaration of 'std::basic_filebuf<char,std::char_traits<char>>' [D:\a\glog\glog\build_Debug\logging_unittest.vcxproj]
C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.37.32822\include\fstream(375,10): message : while compiling class template member function 'void std::basic_ofstream<char,std::char_traits<char>>::_close(void)' [D:\a\glog\glog\build_Debug\logging_unittest.vcxproj]
D:\a\glog\glog\src\logging_unittest.cc(788,12): message : see the first reference to 'std::basic_ofstream<char,std::char_traits<char>>::_close' in 'TestBasenameAppendWhenNoTimestamp' [D:\a\glog\glog\build_Debug\logging_unittest.vcxproj]
D:\a\glog\glog\src\logging_unittest.cc(786,12): message : see reference to class template instantiation 'std::basic_ofstream<char,std::char_traits<char>>' being compiled [D:\a\glog\glog\build_Debug\logging_unittest.vcxproj]

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (931323d) 64.14% compared to head (09075fa) 64.23%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #990      +/-   ##
==========================================
+ Coverage   64.14%   64.23%   +0.09%     
==========================================
  Files          17       17              
  Lines        3327     3327              
  Branches     1125     1125              
==========================================
+ Hits         2134     2137       +3     
  Misses        766      766              
+ Partials      427      424       -3     

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