[RUNTIME] Refactor to enable stackvm in runtime. (#1588)

CMakeLists.txt

Jenkinsfile

cmake/config.cmake

include/tvm/ir.h

include/tvm/runtime/util.h

python/tvm/module.py

src/codegen/codegen.cc

src/codegen/stackvm/codegen_stackvm.cc

src/codegen/stackvm/codegen_stackvm.h

src/runtime/stackvm/stackvm.cc

src/runtime/stackvm/stackvm.h

src/runtime/stackvm/stackvm_module.cc

src/runtime/stackvm/stackvm_module.h

tests/python/unittest/test_module_load.py