binutils/binutils: add BINUTILS_2_21_or_later blind option

Add BINUTILS_2_21_or_later blind option. It will be used to add
conditional support for building 'gold' on versions that have it.

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

 # m68k specific configuration file

 # depends on EXPERIMENTAL

 config ARCH_m68k

     select ARCH_SUPPORTS_32

     select ARCH_DEFAULT_32

     select ARCH_DEFAULT_BE

     select ARCH_SUPPORT_CPU

      help

       The m68k architecture