volk: Add compiler flags for clang in archs.xml

Clang isn't being recognized as gnu, which causes it to build without SIMD instructions.
virtual destructor
CID: 1090040. Fairly straight-forward UNINIT fix in pycallback_object.
CID: 1090040. This bug can't, and doesn't need to be, fixed. Documented.
CID: 1088855. Fixing resource leak issues in fcdOpen
CID: 1090068. Fixes missing virtual destructor issue.
Fixing issue CID 1046354.
Fixing CID 1043304. Lol wut?! ROFL
fix: max_noutput_items is set globally but it should be local to a block.
filter: sets comments for windows to export into Doxygen manual.
filter: fixing windows functions.

Both Kaiser and Blackman windows were wrong. Fixed according to equations in Oppenheim and Schafer. Thanks to Chris Sylvain (KB3CS) for pointing out issues with the Kaiser window.

Added Barlett (triangular) window.
Fixing CID 1043300. Trivial UNINIT fix.

Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
Fixing CID 1043296: Trivial UNINIT.

Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
digital: Fixes CID 1043266
blocks: Fix CID 1088839, 1046407 and 1046395
digital: Fix CID 1043270, minor refactoring
CID: Fixes 1046322

The constructor for fll_band_edge_cc_impl calls
fll_band_edge_cc_impl::design_filter which instantiated
two filter objects that were never freed
filter: fixed frequency translating filter.

Thanks to Achilleas Anastasopoulos for pointing it out and providing the basic patch. Updated QA code here, too, for the changes. Now QA calculates the results from basic principles instead of using a 'gold' set of results.