Add softfp support in min/max kernels

Build and run utests independently of fortran

fix for #1912

Do not try ancient PGI hacks with recent versions of that compiler

should fix #2139

Add option to allow combining USE_THREAD=0 with thread locking support

TST: add SkylakeX AVX512 CI test

for calling from concurrent threads

* adapt the C-level reproducer code for some
recent SkylakeX AVX512 kernel issues, provided
by Isuru Fernando and modified by Martin Kroeker,
for usage in the utest suite

* add an Intel SDE SkylakeX emulation utest run to
the Azure CI matrix; a custom Docker build was required
because Ubuntu image provided by Azure does not support
AVX512VL instructions

Drone CI for arm64 native builds

Move ARMv8/gcc CI job from Travis to Azure

Add NO_AFFINITY to available CMAKE options on Linux, and set it to ON

* Mark iamax_sse.S as unsuitable for MIN due to issue #2116
* Use iamax.S rather than iamax_sse.S for ISMIN/ISAMIN on all x86_64 as workaround for #2116

to match the gmake default. Fixes second part of #2114

TST: Azure manylinux1 & clean-up

DOC: Add Azure CI status badge to README

Address redundant code concern #2113

* remove some of the steps & comments
from the original Azure yml template

* modify the trigger section to use
develop since OpenBLAS primarily uses
this branch; use the same batching
behavior as downstream projects NumPy/
SciPy

* remove Travis emulated ARMv6 gcc build
because this now happens in Azure

* use documented Ubuntu vmImage name for Azure
and add in a manylinux1 test run to the matrix

[skip appveyor]

using aytekinar's Alpine image and docker script from the Travis setup

[skip ci]