1.Remove the code for setting mkldnn environment in the test_calibration.py;
2.Update the cmake file for MKLDNN environment enabling;
3.Update the INT8 inference doc.

test=release/1.3

Cherry-pick signature error to Release/1.3

cherry picked. test=develop

cherry-pick/Fix debug mode in fake_quantize_op (#15693)

cherry pick: fix jitcode name

test=release1.3

test=release1.3

test=release/1.3

* Fix debug mode in fake_quantize_op
* Remove template specialization

remove legacy V2 code in release1.3

test=release/1.3

Fix old FC backward weights descriptor creation

Cherry-pick debug mode fix to release/1.3

test=release/1.3

fix generate doc error in activation ops

test=release/1.3

test=release/1.3

test=develop

fix the build issue on gpu mode for win

1.3/fixci

test=release1.3

test=release1.3

test=develop

Ir inplace pass

optimize density_prior_box_op.h in detect model for cpu

test=develop, fast_install shell for linux and mac

* update_readme

* test=develop