Optimizations for APM's xgene-1 (aarch64).

Credits for the patch go to APM's **Dave Nuechterlein**.

We use Xgene-1 running Ubuntu 14.04 with a custom kernel.
```bash 
$ uname -a
Linux mustang1.lan 3.15.0-rc8+ #5 SMP PREEMPT Thu Jul 31 17:38:57 CEST 2014 aarch64 aarch64 aarch64 GNU/Linux

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/aarch64-linux-gnu/4.9/lto-wrapper
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.9.1-4ubuntu3x4' --with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs --enable-l
Thread model: posix
gcc version 4.9.1 (Ubuntu 4.9.1-4ubuntu3x4)
```

Please tell us what needs to be done for us, such that you can accept the patch.
We can send you a comparison with and without the patch for
strmm.goto
sgemm.goto
strsm.goto