kconfig: print version in .config

Having the crosstool-NG version in the .config helps in case we
want to reproduce the toolchain with the exact same version of
crosstool-NG.

This also reverts #bb73e7632b54.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 #!/bin/sh

 call_to=@@DEFAULT_LD@@

 case "${CTNG_LD_IS}" in

     bfd)    call_to=bfd;;

     gold)   call_to=gold;;

 esac

 exec "${0}.${call_to}" "$@"

 exit $?