compile with macOS support (#4260)
compile with macOS support (#4260)

* compile with macOS support;

* compile with macOS support;

* check both .dylib and .so files;

* satisfy pylint;

* Update Makefile

Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet