fclose: Make last change more maintainable. * m4/fclose.m4 (gl_FUNC_FCLOSE): Define through AC_DEFUN_ONCE. Don't modify REPLACE_FOPEN. * modules/fclose (Depends-on): Add comment. (configure.ac): Don't modify REPLACE_FOPEN. Don't duplicate actions of module 'fopen'. * m4/fopen.m4 (gl_FUNC_FOPEN_ITSELF): Renamed from gl_FUNC_FOPEN. (gl_FUNC_FOPEN): New macro. * modules/fopen (Files): Add m4/fclose.m4, m4/fflush.m4. * m4/close.m4 (gl_FUNC_CLOSE): Define through AC_DEFUN_ONCE.