fix conv_bias_relu fuse bug，x86 conv kernel bug

* bn pattern

* 1. add conv bn fusion pass(conv2d, depthwise_conv2d)
2. modify the graph to ssagraph
test=develop

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* simplify fuse process.

* update from upstream

* close the kernels not empty checker.

* add conv2d, pool2d op and kernels test=develop

* test mobile ci
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* update

* add elementwise_add kernel
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* add elementwise_add unit test
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* enable arm neon
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* remove Repetitive funcs
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* fix lite compile

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* update

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* add the pattern matcher logic. test=develop

* update op_info usage. test=develop

* add concat op, kernel and unitest test=develop

* enable reshape&reshape2 op and add unit test

* enable scale op and add unit test

* fix XShape checking for reshape2 unit test
test=develop

* remove op_desc.hasInput(..) and op_desc.hasOutput(..) to adapt X86 platform
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* remove target() and precision() from softmax, reshape, reshape2 and scale op
fix CopyDataFrom() of TensorHvy
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* alloc memory then copy tensor's data during invoking TensorHvy::CopyDataFrom(...)
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* fix conflicts

* fix kernel registry realted bugs test=develop

* add android emulator document
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* add armlinux docker document

* Error modifying document format
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* enable armlinux compile

* fix deps and skip some build

* update doc and script

* add android simulator

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* arm linux docker and mobile doc

* update

* enable softmax op and add unit test

* move softmax sub-functions to softmax.cc, and move basic math functions to funcs.h

* migrate several ops:
  mean,
  mean_grad
  fill_constant
  square_grad
  elementwise_sub_grad
  mul_grad

* add sdg_op

* fix kernel platform registration issue

* code cleanup

* fix platform typo

* add fc unit test

* refine eigen fc
add cpu info, arm context
init packed sgemm

* enable packed sgemm

* add arm math

* pass fc ut

* follow comments

* code clean - refine ARM

cmake enhancement:

- add lite_cc_library and lite_cc_test

code clean:

- remove ARM feed and fetch kernels, reuse the Host's

remove unnecessary comments