toolchain/crosstool-ng: update config for glibc-based toolchains

Update the version of glibc to be used, since older versions are
broken with the currently-used binutils versions.

Fixes build issues ending with:
    tmpfs/ccvkz3ro.s:33: Error: CFI instruction used without
    previous .cfi_startproc

This new version does not have RPC support, so update the Config.in.

CC: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>