Optimize swap function for POWER10

This patch makes use of new POWER10 vector pair instructions for
loads and stores.

Fix build on FreeBSD/powerpc64le

arm64: Fix nrm2 for input vectors with Inf

Fix double precision nrm2 kernels returning NaN when the
input vectors contain Inf/-Inf.

getarch.c: define OPENBLAS_SUPPORTED for riscv64

Expand the introductory paragraph of the README with links to netlib docs and linear algebra lecture videos

rebase

Define BLAS acronym in README

Temporarily revert to the old NRM2 kernels for ThunderX2/3 and NeoverseN1

Support NVIDIA HPC SDK on POWERPC

Support NVIDIA HPC SDK 20.11 compilers on x86_64

rebase

Move FMA3 option setting to the kernel makefile

Fix undefined CC variable in check for clang+gfortran combo

Fix spurious assumption of cross-compilation on some architectures

rebase

POWER10: Improve copy performance

This patch aligns the stores to 32 byte boundary for scopy and dcopy
before entering into vector pair loop. For ccopy, changed the store
instructions to stxv to improve performance of unaligned cases.

Merge back the release branch into develop to copy tag

Update branch from develop to release 0.3.13

Update Changelog.txt

Co-authored-by: h-vetinari <h.vetinari@gmx.com>

Make fallback from POWER10 to POWER9 depend on new enough compiler