[eigen] intiial ARM NEON results

[Konstantinos Margaritis <markos@xxxxxxxx>]

Hi everyone,

I haven't finished yet, there are 4-5 functions to finish in the ARM NEON port, but here is a benchmark that I 
managed to compile and run:

$ PATH=~/native/bin/:$PATH g++ -O3 -DNDEBUG -DREPEAT=100 -I../ benchVecAdd.cpp -o benchVecAdd -lrt
$ ./benchVecAdd
0.77s  0.0193522 GFlops
$ PATH=~/native/bin/:$PATH g++ -O3 -DNDEBUG -DREPEAT=1000 -mfpu=neon -mfloat-abi=softfp -I../ benchVecAdd.cpp -o 
benchVecAdd -lrt
$ ./benchVecAdd
2.93s  0.0508572 GFlops

~2.64x faster, not bad for a still incomplete port. I'll complete the port in the next days -I've sent an email 
with some NEON questions to the ARM developers themselves- and I'll send a complete patch, asap.

Stay tuned!

Best Regards

Konstantinos