Add autodetection for riscv64

Change computational order in GEMV and GEMM Power6 kernel

1. Remove the FADD insn from the GEMV Transpose code.
  2. Remove the FADD insn from GEMM and ZGEMM code.
  3. Reorder the compution of the Imaginary part in ZGEMM code.

A64FX: Add support for SVE to SGEMV/DGEMV kernels.

Add missing parentheses

Fix axpby_rvv kernels for cases where inc_y = 0

Improve the error message for (p)thread creation failure

The following openblas_utest tests fail when the RISCV64_ZVL128B is
enabled.

TEST 89/103 axpby:zaxpby_inc_0 [FAIL]
TEST 92/103 axpby:caxpby_inc_0 [FAIL]
TEST 95/103 axpby:daxpby_inc_0 [FAIL]
TEST 98/103 axpby:saxpby_inc_0 [FAIL]

The issue is that the vectorized kernels do not work when inc_y == 0.
This patch updates the kernels to fall back to the scalar algorithms
when inc_y == 0, fixing the failing tests.

Signed-off-by: Mark Ryan <markdryan@rivosinc.com>

Implement DYNAMIC_ARCH support for riscv64.  Three cpu types are
supported, riscv64_generic, riscv64_zvl256b, riscv64_zvl128b.
The two non-generic kernels require CPU support for RVV 1.0 to
function correctly.  Detecting that a riscv64 device supports
RVV 1.0 is a little complicated as there are some boards on the
market that advertise support for V via hwcap but only support
RVV 0.7.1, which is not binary compatible with RVV 1.0.  The
approach taken is to first try hwprobe.  If hwprobe is not
available, we fall back to hwcap + an additional check to distinguish
between RVV 1.0 and RVV 0.7.1.

Tested on a VM with VLEN=256, a CanMV K230 with VLEN=128 (with only
the big core enabled), a Lichee Pi with RVV 0.7.1 and a VF2 with no
vector.

A compiler with RVV 1.0 support must be used to build OpenBLAS for
riscv64 when DYNAMIC_ARCH=1.

Signed-off-by: Mark Ryan <markdryan@rivosinc.com>

Suffix BUFFER_SIZEs on POWER as UL to prevent int overflow in computations

Fix NAN handling in ARM/generic SCAL; have AzureCI Windows show errors on failure

Vectorize SBGEMM incopy for Power10 - 4x faster.

Fix build on FreeBSD/powerpc64*

Rewrite "Install OpenBLAS" docs page

Fix core assignment in cpu detection for Intel family 15

Add support for RISCV64_GENERIC in cmake

openblas: fix `BUFFERSIZE` value