I am trying to cross-compile FFTW from build machine x86-64bit Ubuntu Linux to host machine armv7le QNX6.6 neutrino.  
When I build with neon option, the autoconf utility tests that the compiler accepts neon flag and fails because QCC uses
 the build compiler (x86 with no neon support), not the host compiler.  Is there a flag setting I'm missing from below, 
or this an issue with autoconf tools?  Other tests use the host (arm) compiler.  Enabling threads has no effect on this 
error.

Attached is the config.log.

I've since commented out the ./configure lines associated with testing for -mfpu=neon and hardcode the flags in order to
 successfully compile with neon support.

The configure setup is:
ARM_CPU_TYPE=cortex-a9 \
CFLAGS="$CFLAGS $MAKEFLAGS -V4.7.3,gcc_ntoarmv7le -w9 -march=armv7-a -mfpu=neon -mfloat-abi=softfp" \
LDFLAGS="$LDFLAGS -V4.7.3,gcc_ntoarmv7le" \
NM=ntoarmv7-nm AR=ntoarmv7-ar RANLIB=ntoarmv7-ranlib \
STRIP=ntoarmv7-strip CC=qcc LD=qcc \
./configure --host=armv7-nto \
--prefix=$HOME/fftw_test --enable-neon --enable-single \
--enable-threads

Thank you for any thoughts.