libosmo-dsp: Add new recipe (required by gr-iqbal).
gr-iqbal: Use correct dependencies.

gr-iqbal doest not depend on uhd, osmo-sdr or gr-osmosdr. In fact, it is
gr-osmosdr that can take advantage of gr-iqbal if installed.
Merge pull request #12 from csete/griqbal

gr-iqbal: Use correct dependencies and add new recipe for libosmo-dsp