radx 20141123

The formula is updated for a new version (20141123) with some changes:

1. The official website has a link to [a newer version](http://www.eol.ucar.edu/software/radx) (20141125), but it seems they don't keep their link after each release. As the FTP was known to keep archives for some time, an old mirror trick (#268) is put back again.

2. According to `diff -r`, two versions (20141123 vs. 20141125) seem to have only trivial changes in timestamps and some packaging scripts.

3. I don't know much about [science-annex mirror](https://science-annex.org/pub/radx/) used in previous formulas, but it could be used instead if it's guaranteed to be working.

4. `enable-cxx-compat` option is changed to `with-cxx-compat` for **netcdf** dependency. Otherwise it would be kept rebuilding whenever updated.