avr_libc: fix REQUIRES, remove old recipe

The binutils and compiler are built with the secondary compiler on x86,
but the commands are still in the main bin directory so we should't
use the secondaryArchSuffix in the REQUIRES.

Set version requirements between avr binutils, gcc and libc

The libc needs to be built with a recent gcc and binutils so that it
enables support for all the devices supported by the compiler.