build-sys: fix checking Windows platform with _WIN32 macro

[Biswa96]

This replaces WIN32 with _WIN32 macro to check Windows platform.
The correct one is _WIN32 as documented in the official documentation.
https://learn.microsoft.com/en-us/cpp/preprocessor/predefined-macros

[masatake]

I don't know Windows well. However, our own WIN32 is defined in mk_mingw.mak and mk_mvc.mak.
So I guess our WIN32 has nothing to do with _WIN32. Just replacing it may cause trouble.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.39%. Comparing base (1223439) to head (6f1b290).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3977   +/-   ##
=======================================
  Coverage   85.39%   85.39%           
=======================================
  Files         235      235           
  Lines       56609    56609           
=======================================
  Hits        48339    48339           
  Misses       8270     8270           

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[leleliu008]

@Biswa96 WIN32 is a user defined macro https://github.com/universal-ctags/ctags/blob/master/mk_mingw.mak#L10, _WIN32 is a predefined macro which is defined by MSVC or MINGW. what problem have you encountered?

[Biswa96]

The issue was seen in geany project, here geany/geany#3660

WIN32 is a user defined macro

It is not required at all and contradicts with official and well-known _WIN32 macro.

[masatake]

Can we remove -DWIN32 from *.mak files?

[Biswa96]

Can we remove -DWIN32 from *.mak files?

Yes, those can be removed also. I did not notice them at first.

[masatake]

Could you refer to geany/geany#3660 in the commit log?

[Biswa96]

I have added the geany pull request link in commit message.

[Biswa96]

Here are some example of the compiler and linker error in geany which are fixed by this change.

../ctags/gnu_regex/regex_internal.h:424:11: fatal error: alloca.h: No such file or directory
  424 | # include <alloca.h>
      |           ^~~~~~~~~~

../ctags/main/routines.c:463:21: warning: implicit declaration of function 'lstat'; did you mean 'wstat'? [-Wimplicit-function-declaration]
  463 |                 if (lstat (file.name, &status) != 0)
      |                     ^~~~~
      |                     wstat

ld.exe: libctags.a.p/ctags_main_routines.c.obj:routines.c:(.text+0x7cc): undefined reference to `lstat'

[masatake]

Can I ask you to change the prefix of the header of the commit log from "build.main,lex" to "build-sys" ?

build-sys: fix checking Windows platform with _WIN32 macro

[masatake]

@k-takata Thank you for reviewing.