Set FlexiBlas default to AOCL

[AlexKurek]

Description

Set flaxiblas to AOCL permanently. This can be overwritten in runtime by export FLEXIBLAS if needed.
Both during build and runtime flexiblas print gives:

Configured BLAS libraries:
System-wide (/etc/flexiblasrc):
OPENBLAS
library = /opt/OpenBLAS/lib64/libopenblas.so
comment =
AOCL
library = /opt/aocl/5.1.0/aocc/lib/libblis.so
comment =

System-wide from config directory (/etc/flexiblasrc.d/)
NETLIB
library = libflexiblas_netlib.so
comment =
OPENBLAS-OPENMP
library = libflexiblas_openblas-openmp.so
comment =
OPENBLAS-SERIAL
library = libflexiblas_openblas-serial.so
comment =

User config (/home/akurek/.flexiblasrc):
OPENBLAS
library = /opt/OpenBLAS/lib64/libopenblas.so
comment =

Host config (/home/akurek/.flexiblasrc.lof8):

Available hooks:

Backend and hook search paths:
/usr/lib64/flexiblas/

Default BLAS:
System: AOCL
User: (none)
Host: (none)
Active Default: AOCL (System)

Related: #360.