We see frequent CI build failures due to libgcc_s.so missing.
libgcc_s.so is installed multiple times while building libraries, but we
do not pass -S to install(1) when creating the symlink, so there are
windows where an attempt to link against libgcc_s.so fails. Pass -S
like we do when installing the binary lib itself. See r322565.
This is a straw proposal, presumably we should specify -S in a more
generic way, and I'm not sure whether this will cause problems in
!FreeBSD build environments. For instance, on Linux -S means something
else, but maybe it's ok because we should already have bootstrapped
install(1) by this point?