rename: modernize replacement * modules/rename (Depends-on): Add stdio. (configure.ac): Declare witness. * m4/rename.m4 (gl_FUNC_RENAME): Ensure dependency order, and let stdio take care of replacement. * m4/stdio_h.m4 (gl_STDIO_H_DEFAULTS): Add new defaults. * modules/stdio (Makefile.am): Substitute them. * lib/stdio.in.h (rename): Declare replacement. * lib/rename.c (includes): Allow cross-compilation to non-windows machines. * doc/posix-functions/rename.texi (rename): Improve documentation. Signed-off-by: Eric Blake <ebb9@byu.net>