blocks: adding a complex VCO block.
filter: added optional second input that dynamically adjusts resampling rate.
runtime: Fixed runtime SWIG linker error

* gnuradio_runtime_EXPORTS is not defined for SWIG builds by default, so this fix manually sets it for the runtime_swig build
Merge remote-tracking branch 'ncorgan/runtime_swig_fix' into maint
Merge branch 'maint'
build: installing all cmake files into lib/cmake/gnuradio directory.
volk: tests if xgetbv (an avx instruction) is really, truly available. Allows us to build on OSX with GCC.
Merge branch 'maint'
channels: added second channel model that takes in a function to change freq/timing offsets.
Merge branch 'dynamic_channel'
volk: update QA test to use non integer multiples of register sizes to ensure we test the tail cases.
volk: update Volk profiker to use non integer multiples of register sizes to ensure we profile the tail cases.
Merge branch 'maint'
Merge branch 'master' of git.gnuradio.org:gnuradio
modtool: forces another check for include dirs and libraries when looking for gnuradio-runtime. Similar to how GnuradioConfig.cmake looks for components.
Merge branch 'maint'
digital: fix for moving average filter in OFDM equalizer.
Merge branch 'maint'
channels: added _USE_MATH_DEFINES definition to allow use of M_PI in MSVC
Merge remote-tracking branch 'ncorgan/channels_fix'