Fix c build warnings #17634; remove several unused funcs
Removes several unused functions, most importantly `floatify` which util attempts to import from numpy_helper but which does not exist there.

While putting this together I noticed in parsers.pyx a couple occurrences of`print >> sys.stderr, self.parser.warn_msg`.  I guess this is still valid cython, but should probably be updated anyway.

- [x] closes #17634
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
