* m4/glibc2.m4, m4/glibc21.m4: Remove.
* m4/intl.m4, m4/intldir.m4, m4/lock.m4: Remove.
* m4/intdiv0.m4, m4/intmax.m4, m4/inttypes-pri.m4: Remove.
* m4/inttypes.m4, m4/inttypes_h.m4, m4/longdouble.m4: Remove.
* m4/printf-posix.m4, m4/signed.m4, m4/size_max.m4: Remove.
* m4/stdint_h.m4, m4/sys_socket_h.m4, m4/uintmax_t.m4: Remove.
* m4/visibility.m4, m4/wchar_t.m4, m4/wint_t.m4, m4/xsize.m4: Remove.