A few changes from char* to void* where appropriate, and removing of
unnecessary casts.
Much more work on const-ifying the codebase. This round involves some code
changes to make it correct. NOTE!! There will almost certainly be problems
on the non-POSIX ports that will need to be addressed after the const changes
are finished: they will need to be const-ified properly and there may need to
be some changes to allocate memory, etc. as well.
The next (last?) big push for this, still to come, is const-ifying the
filenames in struct file, struct dep, etc. This will allow us to store file
names in the string cache and finally resolve Savannah bug #15182 (make uses
too much memory), among other advantages.
