configure.ac: Check swig supports python and/or ruby
configure.ac: Check swig supports python and/or ruby

Add extra checks for building the python and ruby bindings.

Also use the AS_IF and AS_CASE constructs instead of raw shell syntax.

Linux-Comedi/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib