* build shared lib and enable lto

* reserved for layer and option

* allocator pimpl

* datareader pimpl

* paramdict pimpl, disable copy assign for allocator and datareader

* modelbin pimpl

* net extractor pimpl

* gpu pimple

* disable copy assign vulkandevice, code format

* command pimpl, dummy image readonly

* pipeline pipelinecache pimpl, export platform class

* code format, export simple family

* update ci

* disable lto on android armv7, merge webassembly ci

* link libgcc, fix macos dylib version

* pipeline pimpl, gpu info pimpl

* destroy gpu info after vulkan device

* ignore msvc stl class warning

* fix ncnn_paramdict_get_float return type

* fix vktransfer upload fp16 without flatten, add command test

* package openmp and glslang together
* find glslang targets in lib64
* define version string
* update moltenvk

* fix compiling failure on cxx14

* fix compile failure when NCNN_PIXEL off

* do not export pixel api when NCNN_PIXEL off

* disable squeezenet test when NCNN_PIXEL off

* do not build ncnn2table and examples when NCNN_PIXEL off

* make cmakedefine header independent

* restore platform.h.in

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