[Bug 52374] build on Cygwin fails: error: ‘S_IRUSR’ undeclared (in libs/mpg123)

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=52374

--- Comment #3 from Saulius K.  ---
Wine 7.3 build still fails on Cygwin.

I took a look at the related code block:

--- snip ---
#if (defined(WIN32) && !defined (__CYGWIN__))
        /* MSDN says POSIX function is deprecated beginning in Visual C++ 2005
*/
        /* Try plain old _open(), if it fails, do nothing */
        ret = _open(filename, flags|_O_BINARY, _S_IREAD | _S_IWRITE);
#else
        ret = open(filename, flags,
S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH);
#endif
--- snip ---

... and now I'm not sure whether the 1st or the 2nd part should be activated
when building 3rd party libs.