/usr/lib/gcc/x86_64-linux-gnu/6/libgcc_s.so is in libgcc-6-dev 6.3.0-18+deb9u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | /* GNU ld script
Use the shared library, but some functions are only in
the static library. */
GROUP ( libgcc_s.so.1 -lgcc )
|