Log Message:
FFTW 3.3.6-pl1
Bugfix: FFTW 3.3.6 had the wrong libtool version number, and generated shared \ 
libraries of the form libfftw3.so.2.6.6 instead of libfftw3.so.3.*.

FFTW 3.3.6
The fftw_make_planner_thread_safe() API introduced in 3.3.5 didn't work, and \ 
this 3.3.6 fixes it. Sorry about that.
Compilation fixes for IBM XLC.
Compilation fixes for threads on Windows.
fix SIMD autodetection on amd64 when (_MSC_VER > 1500)