libc/glibc: Remove redundant LIBC_GLIBC_TARBALL config option

Unused since January 2010.

Signed-off-by: "David Holsgrove" <david.holsgrove@xilinx.com>
Message-Id: <7a666ba8c0ea5e8f4b18.1349931190@localhost.localdomain>
PatchWork-Id: 190783

 python

 import sys

 sys.path.insert(0, '@@PREFIX@@/share/gcc-@@VERSION@@/python')

 from libstdcxx.v6.printers import register_libstdcxx_printers

 register_libstdcxx_printers (None)

 end