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.