We need to run it after termux_step_get_dependencies, or else the
symlink might be overridden if dash is a dependency, since it contains
a sh->dash symlink.
termux_step_override_config_scripts is run right after
termux_step_get_dependencies, and feels seems like a logical place to
create the symlink (since symlink is used to make config scripts
executable).
After https://github.com/termux/termux-packages/commit/e34ae5da030d,
llvm-config was created before termux_step_get_dependencies, meaning
that it gets overwritten if libllvm is installed.
Fix this by creating llvm-config in a new function
termux_step_override_config_scripts, that is run right after
termux_step_get_dependencies.
