[m-dev.] trivial diff: tests/*/Mmakefile: delete `.mod' rules

[Zoltan Somogyi]

> tests/general/Mmakefile:
> tests/hard_coded/Mmakefile:
> tests/misc_tests/Mmakefile:
> 	Delete some long obsolete references to `.mod' files.

That's fine, but there is also tests/general/typeclasses/Mmakefile.

Zoltan.