make sure that FFTW is available for the starpufft lib

configure.ac

@@ -512,18 +512,31 @@ AC_MSG_CHECKING(which BLAS lib should be used)
 AC_MSG_RESULT($blas_lib)
 AC_SUBST(BLAS_LIB,$blas_lib)
 
+have_fftw=no
+have_fftwf=no
+have_fftwl=no
+
 PKG_CHECK_MODULES([FFTW],  [fftw3],  [
   AC_DEFINE([HAVE_FFTW], [1], [Define to 1 if you have the libfftw3 library.])
   AC_SUBST([HAVE_FFTW], [1])
+  have_fftw=yes  
 ], [:])
+AM_CONDITIONAL(HAVE_FFTW, [test x$have_fftw = xyes])
+
 PKG_CHECK_MODULES([FFTWF], [fftw3f], [
   AC_DEFINE([HAVE_FFTWF], [1], [Define to 1 if you have the libfftw3f library.])
   AC_SUBST([HAVE_FFTWF], [1])
+  have_fftwf=yes  
 ], [:])
+AM_CONDITIONAL(HAVE_FFTWF, [test x$have_fftwf = xyes])
+
 PKG_CHECK_MODULES([FFTWL], [fftw3l], [
   AC_DEFINE([HAVE_FFTWL], [1], [Define to 1 if you have the libfftw3l library.])
   AC_SUBST([HAVE_FFTWFL], [1])
+  have_fftwl=yes  
 ], [:])
+AM_CONDITIONAL(HAVE_FFTWL, [test x$have_fftwl = xyes])
+
 PKG_CHECK_MODULES([HWLOC], [hwloc], [
   AC_DEFINE([HAVE_HWLOC], [1], [Define to 1 if you have the hwloc library.])
   AC_SUBST([HAVE_HWLOC], [1])

examples/Makefile.am

@@ -19,7 +19,11 @@ AM_CPPFLAGS = -I$(top_srcdir)/include/ -I$(top_srcdir)/examples/
 
 TESTS = $(check_PROGRAMS)
 
+if HAVE_FFTW
+if HAVE_FFTWL
 SUBDIRS = starpufft
+endif
+endif
 
 check_PROGRAMS =