Remove stray architechture_independent flags

This flag should be used for packages which do not contain architecture-specific files. Compiled binaries are such a file, and these packages contain them.

Please backport this patch to `groovy-devel` as well, and a release bump would be appreciated.

Thanks!

See:
* http://www.ros.org/reps/rep-0127.html#architecture-independent
* https://github.com/ros-infrastructure/bloom/pull/270