ldconfig not found dpkg error

correct the error during apt install from dpkg that reports ldconfig not found in path.

the file doesn't exist in the image, so add it back. the following fixes the issue completely

apt-get download libc-bin

dpkg --extract ./libc-bin_*.deb ./deb

cp ./deb/sbin/ldconfig /sbin/

apt-get install --reinstall libc-bin