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.
Henrik Grimler