/usr/lib/gcc/x86_64-linux-gnu/4.6.3 is in gcc-4.6-base 4.6.3-1ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc/x86_64-linux-gnu/4.6
/usr/lib/gcc/x86_64-linux-gnu/4.6