* Fix compiling bug in android_armv7_demo : cxx demo can not compile properly because demo' android version is different from that of library file (#2308)

link armv7 demo to android-23 to make sure the demo can compile properly
cxx demo can not compile properly because demo' android version is different from that of library file, we fix this bug by linking armv7 demo to android-23

* Add 'inference' folder into build.lite.x86, 'inference' folder contains head files、library files and demo of x86 compiling (#2301)

Add inference folder into build.lite.x86, build.lite.x86/inference folder contains head files、library files and demo of x86 compiling

* we can build x86 dynamic library by `build.sh x86`  (#2270)

* remove dynamic library compiling from `ci_build.sh  build_test_server` (#2275)

* cherry-pick model-tailoring into release/v2.1.0 test=develop

* [python api] add armlinux supported and publish paddle-lite python lib & demo

* add cuda build
test=develop

* fix building model_optimize_tool error on mac, test=develop

* fix model_optimize_tool build error, test=develop

* fix gemm_int8, gemv-int8 and conv-int8 math function, add float bias

* change conv impl

* neon int8 kernel support float bias

* arm compute kernel support float bias

* add math_test target

* add tensor utils for testing, fix sgemm ut error

* add gemm_int8 unit test, support float bias

* fix build script

* add conv compute unit test for arm

* fix build script, test=develop

* fix fp32 dw conv3x3s1, test=develop

* add fp32 dw conv3x3s1, test=develop

* add armv7 fp32 dw conv3x3s1, test=develop

* add fp32 depthwise conv3x3s2, test=develop

* fix fp32 conv3x3 depthwise build error, test=develop

* fix gemm_like conv trans weights error, test=develop

* fix int8 depthwise conv3x3 error, test=develop

* turn on all test for arm fp32 conv, test=develop

* fix int8 conv1x1 error

* fix int8 direct conv3x3s1 error, test=develop

* fix int8 direct conv3x3s2, test=develop

* turn on all test for arm int8 conv, test=develop

* fix int8 fc error, change mobilenetv1-int8 ground-truth result to fluid, test=develop

* remove debug info, strip ut binary, test=develop

* fix conv compute error, test=develop

* change Init() to ReInitWhenNeeded(), test=develop

* fix code style, test=develop

* remote engine_test, test=develop

* fix building server tests error, test=develop

* fix sdot clang build error, test=develop

* fix sgemm ut timeout error, test=develop

* fix clang build error, test=develop

* turn off math basic test due to ci time out, test=develop

* fix conv_int8 ut error, test=develop

* fix ios build script, test=develop

* add ios tiny publish target, test=develop

* fix ios build scrip, test=develop

* merge build_ios.sh to build.sh, test=develop

* ios support BUILD_EXTRA, test=develop

* [Publish] fix publish compile

* update build.sh to clean build dir

move cmake functions to lite.cmake