only Linux system is supported now.

change the default value of `ENABLE_AKG` to off, and controlled by option `-K`.
the `ENABLE_AKG` is auto enabled when `ENABLE_GPU` or `ENABLE_D` is on.
since now, we can use `ENABLE_AKG` to control the compilation of graphkernel
and akg codes.

fix usage description for option "-K", it should be "[-K on|off]".

LLVM is required by akg for cpu kernels, so AKG for cpu is default disabled now.

This reverts commit b077aa1cab.

Revert "[feat] [assistant] [I3T96X] add new Dataset operator LibriSpeechDataset"

This reverts commit 4e6f7dc97d.

delete pass_registry_test.cc

comment  hiai_nlu_model_multi.pb related  line

Merge pull request !19646 from zhangzhaoju/ms_master_build

solve build errors while change BUILD_PATH

Merge pull request !19316 from yeyunpeng2020/java

Merge pull request !18935 from zhoushan33/flclient0626_om

Merge pull request !17856 from ehaleva/train_lenet_java_example

From: @YeFeng_24
Reviewed-by: @hangangqiang,@zhanghaibo5
Signed-off-by: @hangangqiang

From: @xu_anyue
Reviewed-by: 
Signed-off-by:

From: @nicholas_yhr
Reviewed-by: @zhoufeng54,@zhoufeng54,@xsmq
Signed-off-by: @zhoufeng54,@xsmq

From: @sunsuodong
Reviewed-by: @zhanghaibo5,@zhang_xue_tong
Signed-off-by: @zhanghaibo5,@zhang_xue_tong

From: @lzkcode
Reviewed-by: @zhang_xue_tong,@zhanghaibo5
Signed-off-by: @zhang_xue_tong

From: @YeFeng_24
Reviewed-by: 
Signed-off-by:

From: @wangyanling10
Reviewed-by: 
Signed-off-by:

From: @luoyang42
Reviewed-by: @tiancixiao
Signed-off-by: