Add env variable OMP_ADAPTIVE to control OMP threadpool behaviour

LoongArch64: Add DYNAMIC_ARCH support

* fix detection of Neoverse V1 and user-enforced selection of N2

This fixes compilation in the following case:

$(MAKE) USE_OPENMP=1 USE_THREAD=1 NO_LAPACK=0 DYNAMIC_ARCH=1 \
DYNAMIC_LIST="HASWELL SKYLAKEX ATOM COOPERLAKE SAPPHIRERAPIDS ZEN"

Support Zhaoxin/Centaur kh40000 as ZEN

Signed-off-by: JonasZhou <JonasZhou@zhaoxin.com>

WIP casts and cleanups

OpenBLAS: aarch64: Add neoverse-v1/n2 architecture specifics

* Move accesses to the overflow flag into the scope of the blas lock

*  return OMP places (if available, or SC_NPROCESSORS_CONF) for maximum thread count when built with OpenMP

Add pointers to the definition of the hardware capability flags in glibc
and describe how they relate to the levels CPU_Z13 and CPU_Z14 for
optimized kernels.

To aid identifying available hardware capabilities and in debugging
potential build issues, dump their value in dynamic_arch_init() when
OPENBLAS_VERBOSE is set to 2 or higher.

Signed-off-by: Marius Hillenbrand <mhillen@linux.ibm.com>

On s390x, the run-time detection for DYNAMIC_ARCH and the compile-time
choice in cpuid_zarch use different methods for identifying the
supported CPU features. To make cpuid_zarch future-proof and both easier
to maintain, switch cpuid_zarch to the same mechanism as DYNAMIC_ZARCH
(i.e., derive the supported CPU features from hwcap flags) and share
code between both (in a new header cpuid_zarch.h).

Signed-off-by: Marius Hillenbrand <mhillen@linux.ibm.com>

Remove extraneous qualifiers from struct definition