Fix dynamic dependency on libssp.so with -fstack-protector-strong when cross-compiling from macOS to Linux

[deciduously]

The current darwin to Linux GCC cross-toolchains produces executables with a runtime dependency on libssp.so when compiling with -fstack-protector-strong. The Linux GCC toolchains use the built-in machinery from libc for this feature, resulting in executables without this additional runtime dependency.

Reconfigure the Darwin cross toolchain build to match the behavior on Linux.