libc/glibc: add 2.13

Patchset provided by "Ioannis E. Venetis" <venetis@mail.capsl.udel.edu>
http://sourceware.org/ml/crossgcc/2011-04/msg00072.html
http://sourceware.org/ml/crossgcc/2011-04/msg00073.html

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

# Alpha specific configuration file

config ARCH_alpha

    select ARCH_SUPPORTS_32

    select ARCH_DEFAULT_32

    select ARCH_USE_MMU

    select ARCH_SUPPORT_CPU

    select ARCH_SUPPORT_TUNE

    help

      The Alpha architecture.