libc/glibc: use the multi-inclusion capability of the new kconfig

Now that kconfig can include a file multiple times, link the glibc/eglibc
common stuff to two .in.2 files.

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

 # Alpha specific configuration file

 ## select ARCH_SUPPORTS_32

 ## select ARCH_DEFAULT_32

 ## select ARCH_USE_MMU

 ## select ARCH_SUPPORT_CPU

 ## select ARCH_SUPPORT_TUNE

 ##

 ## help The Alpha architecture.