tweaked fl_wcwidth.c and mk_wcwidth.c to supercede system wchar_t

fl_wcwidth.c has a typedef unsigned int wchar_t; and
mk_wcwidth.c has an #if 0 to stop #include <wchar.h>



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@7530 ea41ed52-d2ee-0310-a9c1-e6b18d33e121