Merge 0.3.18 back into develop to copy tag

Merge from develop for 0.3.18

* Update Changelog for 0.3.18

Update Alpine version used in Azure CI

Fix out of bounds read in ?llarv (Reference-LAPACK PR 625)

Make sure that Netlib LAPACK respects FFLAGS

OpenBLAS allows users to specify `FFLAGS` and then uses `override` to append additional
options. However, without such an override in lapack's make.inc, lapack would use the external
FFLAGS, rather than the ones being computed by OpenBLAS. For example the `DEBUG=1` flag
would not apply to LAPACK code. This is all a bit messy but forced by the integration with netlib
lapack. Note that `CFLAGS` already has this override for the same reason. It is possible that
other variables here should have a similar override, but I think for most of the other ones, OpenBLAS's
build system does not append to the flags passed in by the user.

x86_64: BFLOAT16: fix build warning

Makefile.system: adjust mipsel/mips64el ARCH variables

When building for MIPS{64} little-endian variants, the included makefiles
should be the same as for the big-endian.

There are already some adjustments being done for some ARCH names.
This change adds the ones for the `mipsel` and `mips64el` names, so that
the Makefile.mips{64} files get included.

This comes as a result of: https://github.com/openwrt/packages/issues/16649

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Update README.md

Modify ARMV8 kernels to leave x18 unused as it is reserved on OSX

[POWER] Remove unused variable warnings.

Silence compiler warnings about uninitialized variables

actual initialization is via the _mm_cmpeq_ep18, which I've seen claimed to be the fastest way to set an xmm register to all 1s

Remove extraneous qualifiers from struct definition

Add casts to fix compiler warnings for SkylakeX sasum/dasum

Rework generation of BFLOAT16 objects in CMAKE builds and fix missing CBLAS_XERBLA