Prevent DYLB from being loaded in darwin binaries

[mx-psi]

macOS has a similar mechanism to LD_PRELOAD in Linux called DYLD_INSERT_LIBRARIES. Our current macOS binaries honor this environment variable, while the Linux ones do not. It is a good security practice to prevent usage of said environment variable to avoid preloading of arbitrary dynamic libraries.

To harden our binaries we can follow this StackOverflow answer advice.

Reported as part of the recent security audit.