Summary:

In multi-threaded applications where we have multiple inferences on the
same model in parallel (consider e.g. a TTS system handling multiple
requests), it can be useful to share the parameters of a model amongst
these multiple instances. This improves the cache utilization behaviour
of the system, as multiple cores can use the same set of weights instead
of evicting the identical copies of weights in a shared cache.

As the underlying `NDArray` instances in `data_entry_` implement a
ref-counted based sharing system, this is a simple modification of the
`GraphRuntime::LoadParams` logic to instead copy parameters from an
existing GraphRuntime instance. This is a little ugly in that we need
both the pre-existing GraphRuntime instance, as well as the 'serialized'
params (since we need to know the set of names we should copy), but
without imposing additional assumptions (i.e. storing the set of param
names in GraphRuntime, and enforcing that shared param names are
identical to the parameters set in the preceding `LoadParams` call),
this seems unavoidable.

Test Plan:

Unit test added.

* [HEADER] ASF header dir=include

* [HEADER] ASF Header dir=src

* [HEADER] ASF Header -dir=python

* [HEADER] ASF header dir=topi

* [HEADER] ASF Header dir=nnvm

* [HEADER] ASF Header -dir=tutorials

* [HEADER] ASF Header dir=tests

* [HEADER] ASF Header -dir=docker

* fix whitespace

* [HEADER] ASF Header -dir=jvm

* [HEADER] ASF Header -dir=web

* [HEADER] ASF Header --dir=apps

* [HEADER] ASF Header --dir=vta

* [HEADER] ASF Header -dir=go

* temp

* [HEADER] ASF Header --dir=rust

* [HEADER] Add ASF Header --dir=cmake

* [HEADER] ASF Header --dir=docs

* [HEADER] Header for Jenkinsfile

* [HEADER] ASF Header to toml and md

* [HEADER] ASF Header to gradle

* Finalize rat cleanup

* Fix permission

* Fix java test

* temporary remove nnvm onnx test

* use LLVM linker

* error message improved in case of filenotfound

* linting error fixed

typo: Xlinx => Xilinx

* fix a issue when running with graph_runtime_debug in python;

* add support to `debug_get_output` in python;

* comply with the linter;

Signed-off-by: Zhebin Jin <zhebin.jzb@alibaba-inc.com>

* Implement C code generation with tests

* Code cleanup

* Implement C code generation with tests

* Code cleanup

* tabs to spaces

* make lint compliant

* update export_library and reserve unique C keywords

* move ReserveKeywordsAsUnique to codegen_c

* some documentation and code cleanup

* use tvm.contrib.util for tempdir in testcases

This fixes issues with failing tests on PowerPC.