wx: Only call XInitThreads for linux

Turns out OSX also returns 'posix' for os.name. This limits it to
linux only. Note that it's purely cosmetic because on OSX it would
just print a warning but not prevent anything from working.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
wxgui: Make sure to only start the flow graph once all init is done

Currently we start the flow graph in the stdframe constructor.
However at that point, the frame isn't attached to the app and it's not
"shown" yet which means some UI operations can still fail.

This is a race condition which happens on OSX. You can reproduce it on
linux as well by adding a sleep(1) after starting the flow graph.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
runtime: Disable CPU_SET macros for FreeBSD.
qtgui: fixed thread-safety in GRC variable-type blocks
qtgui: fixed naming of classes for long-term use.
volk: clang sets GNUC_MINOR only to 2, so we need to check if we're building with clang. This patch enables xgetbv for clang >= 3.0.
volk: some versions of clang have problems with cvtpi32_ps.

We make a separate cmake check here for xgetbv and cvtpi32_ps and set definitions accordingly.
volk: test for clang version; if less than 3.2, disable SSE4a machine due to a bug in the compiler support.
filter: fixed an issue with filter delays for interp and rational_resampler filters.
analog: additional docs for noise sources.
cmake: If Ice 3.4 found, check version of GCC and disable if >= 4.7.
volk: modifying tests for AVX and SSE4a support in compiler/CPU.
grc: fix variable vlen for grc generated hier blocks
build: fixing various warning from clang.

Addresses iss #586; adapted for current set of warnings after patches since this issue was posted.
volk: negate real part of 32fc_s32f_power_32fc to fix results.

Addresses issue #629.
cmake: FindICE wasn't looking in the cmake prefix properly to find the include files.
Merge remote-tracking branch 'smunaut/fix_wx' into maint
build: fixed a warning on OS X.
build: of course this wouldn't have worked. Now fixing the compiler warning on OS X.