test=develop

* Initial support for XPU
* Fix compiling errors of XPU
* Move XPU op kernel bridges from backends to kernels to fix deps order
* Change the namespace and directory of XPU bridges
* Add XPU SDK
* Fix header files and namespace of XPU SDK
* Add unit tests for relu and conv2d ops
* Restore the modification of paddle_api_test
* Supports simple model which contains only a relu layer
* Add compiling scripts for XPU
* Fix compiling errors of XPU
* Add comments for XPU LoadModel and BuildModel

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

* add cuda build
test=develop

* Make armlinux compile libpaddle_light_api_shared.so
test=develop

(1)modify tiny publish so to make it excutable
(2)modify the bug of compiling in armlinux
(3)change 3 full publish so into 2

* fix: fix build_fpga.sh WITH_TEST=OFF
     add build_fpga publish_inference fpga dir

* fix: fix build_fpga.sh WITH_TEST=OFF
     add build_fpga publish_inference fpga dir
     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

* fix building ios tiny publish lib error

* support setting cluster and threads in MobileConfig

* fix build error, test=develop

* fix building server publish error, test=develop

move cmake functions to lite.cmake