libc-glibc: remove 2.3.6

This is an obsolete version which is no longer used by any sample (the only
user, the ia64 sample, has been removed).

It also makes the code path a bit complex, with twists just to accomodate
that version. Removing the version will make those twists go away, and
will ease commonalisation of glibc and eglibc in the future (hopefully!).

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

 # Blackfin specific configuration file

 config ARCH_blackfin

     select ARCH_SUPPORTS_32

     select ARCH_DEFAULT_32

     select ARCH_DEFAULT_LE

     select ARCH_SUPPORT_ARCH

     select ARCH_SUPPORT_CPU

     select ARCH_SUPPORT_TUNE

     select ARCH_SUPPORT_FPU

      help

       The Blackfin architecture