Macsim_internal is missing?

[farzonl]

for build -q there is a reliance on git submodules. the submodule for macsim_internal points nowhere: https://github.com/gthparch/macsim_internal/tree/1de5c708e00bf9319e8574013750c0233cdaa542

assuming this is no longer needed, is it safe to remove?

[farzonl]

@pranith