libc/glibc: print name of skipped addon

When trying to extract an already present (aka bundled) addon,
print the name of that addon, for clarity, and to help analyse
the build.log post-mortem.

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

 # m68k specific configuration file

 ## select ARCH_SUPPORTS_32

 ## select ARCH_DEFAULT_32

 ## select ARCH_DEFAULT_BE

 ## select ARCH_SUPPORTS_WITH_CPU

 ##

 ## help The m68k architecture