smalloc: remove module

Bye bye, smalloc. I'm not sure why this was still here; it was removed
in 70d1f32 and hasn't worked since. It wasn't packaged in the
binary, either.

Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Sakthipriyan Vairamani <[email protected]>
Reviewed-By: Сковорода Никита Андреевич <[email protected]>
Reviewed-By: Ben Noordhuis <[email protected]>
PR-URL: #3099

Author: brendanashworth