Preprocessor defines for function prototypes according to XPG4

The following functions are defined differently in the XPG4 Standard and in Amendment 1:

fputwc, putwc, putwchar, wcschr, wcsrchr, wcstok

The preprocessor defines _XOPEN_SOURCE_EXTENDED and _XOPEN_SOURCE can be used to control whether the prototype of the function compliant with XPG4 or Amendment 1 is to be made available.

If you do not set _XOPEN_SOURCE_EXTENDED and _XOPEN_SOURCE, the prototype that complies with Amendment 1 is offered.

If you set _XOPEN_SOURCE_EXTENDED or _XOPEN_SOURCE, the prototype that complies with XPG4 is offered.