Reported by Julia project. JuliaLang/julia#9084

c_check: set $hostarch to x86_64 instead of amd64

fix fortran compiler detection on FreeBSD

`uname -m` returns "amd64" on some systems.

On FreeBSD, passing extra options to `which` causes it to report a non-zero status:

```
$ which gfortran48 -m64
/usr/local/bin/gfortran48
$ echo $?
1
```

```
$ which gfortran48
/usr/local/bin/gfortran48
$ echo $?
0
```

If you "make PREFIX=/path/to/OpenBLAS install" ,
The config file will be located in /path/to/OpenBLAS/cmake

Then, you can use "find_package(OpenBLAS)" at CMake.
cmake -DOpenBLAS_DIR=/path/to/OpenBLAS/cmake ..

xgene-1 (aarch64).
Merge branch 'benedikt-huber-dave-patch' into develop

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

1) general system updates to support armv8 better.  Make all did not work, one needed to supply TARGET=ARMV8.
2) sgem 4x4 kernel in assembler using SIMD, and configuration changes to use it.
3) strmm 4x4 kernel in C.  Since the sgem kernel does 4x4, the trmm kernel must also do 4xN.

Added Dave Nuechterlein to the contributors list.

add SYMBOLPREFIX and SYMBOLSUFFIX makefile options

for adding a prefix or suffix to all exported symbol names in the shared library
Useful to avoid conflicts with other BLAS libraries, especially when using
64 bit integer interfaces in OpenBLAS

Note that since OSX does not have the objcopy utility, setting these options
to non-empty values on Mac requires the objconv tool, available (GPL license)
from http://www.agner.org/optimize/#objconv

Enabled GEMM3M functions

Add HASWELL to TargetList.txt

The Intel "Haswell" architecture is missing from the list of build targets.

optimized multithreading lower limits

Optimized cgemv and zgemv kernels