* zfh zvfh xtheadvector infra
* dispatch for rvv and xtheadvector
* dispatch for non-vector zfh
* port xtheadvector recp rsqrt trunc
* general rvv gemm
* c906 and c910 ci
* old tuple code clean
* update riscv64 ci
* update build doc
* drop old th1520 toolchain

* benchmark: Don't use std::thread when NCNN_THREADS is OFF

* Add wasi support

cmake -B build -DCMAKE_BUILD_TYPE=Release \
	--toolchain ${wasi_sdk}/share/cmake/wasi-sdk.cmake \
	-DNCNN_RUNTIME_CPU=OFF \
	-DNCNN_DISABLE_EXCEPTION=ON \
	-DNCNN_THREADS=OFF

cmake --build build

After build, you can run benchncnn on cmdline with wasmtime:
wasmtime --dir . benchncnn

with `/openmp:llvm` compile option

* promote vfpv4 for auto fp16 storage conversion

* always report neon and vfpv4 for arm64

call omp_set_num_threads with zero num_threads is implementation defined

* force global cpu info initialization

* sanitize zero nT

* new api for detecting arm midr and a53 a55 arch info wrapper

* let a35 be a53 :P

* a53 bf16s

* detect running core

* find cpu cache size from sysfs

* android l3

* make g_thread_affinity_mask singleton

* global mask

* get cpu l2 cache size and resolve gemm tile size

* optimize constant tile K

* fix per-core l2 cache detection, better macos cpu cluster topology discovery

* get_physical_cpu_count api family

* set default to physical big cpu

* always treat smt core as big core

* is_smt_cpu

* get max freq mhz on windows

* windows thread affinity