* Support Ingenic X2000 & T40

T40 claimed to have MIPS32R2 with MSA, but tested not working on my unit, so set to mips32r2 without MSA.

* Add Ingenic T40XP benchmark result

Co-authored-by: tsuibin <tsuibin@loongson.cn>

* fix iOS minimum version,when used Vukan 1.2
* Update IOS mininum version to 9.0

* SSE2: BatchNorm

* Fixed batch norm in AVX configuration

* Optimized register size switch

* Attempt to pass CI

* Attempt to pass CI

* Bias op

* Element wise ops

* Support packing on x86 by default

* Fixed macro range in bias

* Use aligned read for packed data

* Update testutil.h

* Update pooling_x86.cpp

* Support wasn SIMD

* Fix emscripten compiler flags

* fix build

* more ci fix

* concat x86 pack4

* flatten x86 pack4

* more x86 pack4

* ci pass

* fix

* enable sse2 mathfun

* enable --experimental-wasm-simd

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

Test platform: ZYNQ 7020, there is vfpv3 but isn't vfpv4

* [build] add toolchain file w/o stdcxx dependency

* [build] link m and gcc lib explicitly

* [ncnn] complete simple stl impl

* [ncnn] adapt for ncnn simplestl

* [test] adapt for ncnn simplestl

* [ncnn] fix missing algorithm and list when simplestl disabled

* [ncnn] fix guard for operator new and delete

* [style] fix the code style

* [build] fix build failed on darwin and emscripten

* [ci] do not import cxx to avoid operator conflict

* [ncnn] add temporary partial_sort impl using bubble sort

heap sort should be used for better perf.

* [ncnn] add std greater and less function

* [ncnn] fix placement new operator overload

* [ncnn] add operator delete with size info

* [build] disable exception, rtti, example and tools when simplestl on

* [build] add toolchain for arm simplestl

* [build] add toolchain for aarch64 simplestl

* [ncnn] move initializer to constructor

* [ncnn] use deteiled type instead of auto

* [ncnn] use plain lib name in target_link_libraries

* 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

* added fp16 weight storage version

* Small changes

* Fixed fp16 weight storage layers

* fix innerproduct

* fix loop error

* Fix windows build.

Disable fp 16 conversion when detecting int8 weights.

Implement requested changes.

* Restyled by clang-format

* Restyled by astyle

* Restyled by clang-format

* Restyled by astyle

* Update option.cpp

Set fp16 storage based on vulkan being used or not.

* added ability for storing state in lstm layer

* added avx lstm

* added arm lstm

* fix innerproduct activation location and add 4 parallel channel version

* Restyled by clang-format

* Restyled by astyle

* Restyled by clang-format

* Restyled by astyle

* revert arm file

* commit before switch

* implement requested changes

* Restyled by clang-format

* Restyled by astyle

* Restyled by clang-format

* Restyled by astyle

* More x86 optimized implementations of common layers.

Added LSTM layers for arm and x86 + a ctest to verify the layer accuracy

Added fp16 innerproduct for arm

* fix non avx build

* Add fp16 arm compiler and cpu checks. Remove statefullness from LSTM implementation.

* Fix build check for fp16 arm

* Bypass lstm_fp16 if not supported

* Build order was incorrect

* fix std::min missing in windows build

* Restyled by clang-format

* Restyled by astyle

* Restyled by clang-format

* Restyled by astyle

* attempting to fix gnu build by enabling: -mfp16-format=ieee to fix the missing __fp16 type

* remove double "fix"

* Specify ieee fp16 format

* implement requested changes

* fix arm non-fp16 build

* fix arm lstm

* Restyled/pull 1881 (#15)

* Restyled by clang-format

* Restyled by astyle

* Restyled by clang-format

* Restyled by astyle

Co-authored-by: Restyled.io <commits@restyled.io>

* Check blob size on arm lstm

* fix styling

Co-authored-by: Restyled.io <commits@restyled.io>

* try checkout v2 to resolve some ci issue

* Add mips architecture optimization support

* Add mipsisa32r6 toolchain files

* Add AbsVal_mips layer

* Remove unused constructor override

* Keep the same programming style with upstream

* Add Bias_mips layer

* Add Clip_mips layer

* Update copyright header

* Add mips-mti-gnu compile to travis

* Add codescape mips toolchain config

* Update the toolchain comments

* Fix conflicts in travis config file

* Add travis status in README.md

* add relative README_CN.md;
* obtain time cost with op->forward().

* adding how to build for jetson

* update build instruction for NVIDIA Jetson

The latest CMake generates lots of the same warning message as below,
when building ToT ncnn for iOS:

  CMake Warning (dev) at toolchains/ios.toolchain.cmake:451 (set):
    implicitly converting 'string' to 'STRING' type.

This PR fixes 'string' to 'STRING' to suppress the warning messages above.