remove fftpack sources We now require FFTW to perform FFT calculations. * liboctave/external/fftpack: Delete directory and all files. * liboctave/external/module.mk: Update. * lo-fftpack-proto.h: Delete. * liboctave/numeric/module.mk: Update. * CMatrix.cc, CNDArray.cc, dMatrix.cc, dNDArray.cc, fCMatrix.cc, fCNDArray.cc, fMatrix.cc, fNDArray.cc: Require FFTW to compute FFT. * interpft.m, fftconv.m, fftfilt.m, freqz.m, fft.cc, fft2.cc, fftn.cc: Use TESTIF HAVE_FFTW as needed. * NEWS: Note change.

--- a/NEWS	Wed Jul 11 11:20:58 2018 -0700
+++ b/NEWS	Wed Jul 11 17:41:36 2018 -0400
@@ -15,6 +15,9 @@
     However, if the property "IntegerHandle" has been set to "off" then
     the property will return an empty matrix ([]).
 
+ ** We now require the FFTW library to perform FFT calculations.  The
+    FFTPACK sources have been removed from Octave.
+
  ** Deprecated functions.
 
     The following functions have been deprecated in Octave 5.0 and will