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

 #!/bin/sh

 set -e

 printf "Running autoconf...\n"

 autoconf -Wall --force

 printf "Done. You may now run:\n    ./configure\n"