* feat: add denormal options

Flush-To-Zero(FTZ) and Denormals-Are-Zero(DAZ) are modes that bypass IEEE754 methods of dealing with denormal floating-point numbers on x86_64 and some x86 CPUs.

* feat: Integrate `flush_denormals` into `Extractor::extract`

* chore: replace global variable with `ThreadLocalStorage`

* recognize apple M1

* macos ios cpuset and thread affinity

* big little cpu topology for macos and ios

* silence affinity not supported error

* openmp on webasm works

* fix compile flags

* dynamic kmp runtime initialization

* clang simpleomp ci

* fix dispatch on unique cpu

Co-authored-by: nihui <shuizhuyuanluo@126.com>

* runtime cpu dispatch

* force thread one

* disable openmp for coverage

* simplify test layer

* print NCNN_TARGET_ARCH

* less ci build variants

* weight fp16 storage option

* test convdw int8

* apple a12 a13

* ncnn_add_layer ncnn_add_shader cmake macro

* add copy_cut_border check; fix compile warnings

* 去掉对stl的依赖

* 头文件名，push_back改正

* 去掉构造托管

* 好像是折腾

* data 的返回改为指针，非指针引用

* resize一处写错

* stdint

* 加入c_str

* 改文件名为小写

* NCNN_SIMPLESTL option

* simplestl default to OFF

* Update linux-x64-cpu-gcc.yml

* Update linux-x64-cpu-gcc.yml

* Update linux-x64-cpu-clang.yml

* drop functional header

* arm32 arm64 simplestl ci

* 修改一处内存泄漏, 去掉编译器警告

* resize时默认量的bug

Co-authored-by: nihuini <nihuini@tencent.com>
Co-authored-by: nihui <shuizhuyuanluo@126.com>

* Add: pi3.toolchain.cmake - CMake variables for Pi3 compilation.

* Modify: CMakeLists.txt - Add definitions for Pi3 compilation.

* Modify: src/cpu.cpp - Use getpid() if -PI3 is used.