Remove the .mdbcomp_modules files in 'realclean'

In slice/ and deep_profiler/, when 'realclean' was executed
it removed copies of the .m files from mdbcomp/ but did not remove the
.mdbcomp_modules file.  When 'make' was executed again the .m files would
not be copied back into either slice/ or deep_profiler/

This patch fixes this problem by removing .mdbcomp_modules when 'realclean'
is executed.

deep_profiler/Mmakefile:
slice/Mmakefile:
    As above.
Add the .mdbcomp_modules files to .gitignore

deep_profiler/.gitignore:
slice/.gitignore:
    As above.