Update Makefile

[doing-science]

added -fpermissive flag to resolve compile error due to -Wincompatible-pointer-types changing from a warning to an error in gcc.

[Narrat]

Are those incompatible types absolutely unavoidable?
If not, maybe adding -Wno-error=incompatible-pointer-types is better, so the warnings at least remain?

[doing-science]

I think you're suggestion is the correct way to go. I was focused on solving the build issue and not thinking of the potential repercussions toward solving the root of the problem.