Issue:
git clone latest TVM/VTA and run VTA on xilinx FPGA board, application
crashed due to the "call stack overflow" which caused by a infinite recursive
function call. this issue ever happen before and get addressed by PR 3843.

Analysis:
seems like de10-nano driver PR  used old code base then the  logic change
of 3843 get eliminated.

Solution:
add the logic back.

The -mfloat-abi hard option does not work for LLVM < 6.0 as it is ignored.
This adds a fatal error when using unsupported LLVM versions so that the failure
is not silent.

* Fix VM invoke with set_params

* add test

* tweak

In current implementation HIDE_PRIVATE_SYMBOLS hides symbols from TVM
itself but not from its dependent libraries. This is problematic when
other third-party libraries with the same symbols are linked to the
same executable.

One example is using TVM with Mesa OpenCL drivers: they depend on LLVM
and load its shared libraries with RTLD_GLOBAL flag, which results in
conflicts with LLVM symbols that TVM uses. Arguably this particular
issue belongs to Mesa (here's their tracking bug:
https://gitlab.freedesktop.org/mesa/mesa/issues/236) but in general
that's the right thing to do regardless of this particular bug.

Note that I'm not enabling this functionality for Darwin as in my
earlier tests their linker didn't seem to understand "--exclude-libs"
(but I don't have test platform ATM to double-check).

fix some typos

The tensorflow zeros_like operation provided in array_ops.py produces directly a tensor with zeros
without a graph, using only the shape and type of the input. This imposes the use of gen_array_ops.py
that produces both a tensor and a graph so a comparison between tflite and tvm can be done.

@zhiics @icemelon9

* [Relay][VM] Add more passes to VMCompiler

* Check build config

* Add todo

* fix

* tweak

* save

save

redo max test

save

address comment

fix

* address comment

* increase rtol

* address review comment

* [Relay][Op] Add instance norm op

* mend

[Relay][Op] Add instance norm op

* [TF][Op] Add TF op Where

* improve tests

* add tests for vm

* Add op argwhere

* Move shape func to _algorithm.py

* Add lint rule

* Raise exception if rank is not supportted

* move argwhere to transform

* Add argwhere example

* Fix lint

* Add 1-d support

* cleanup

* Add more dtype support

* CR comment

* Improve error message

* Docs

* raise exception

* [topi] add ARM v8.2 udot (uint8) support

* fix test case

* fix common conv2d schedule

* add back fp32_time in test

* fix lint

* fix doc, add support for int32_lanes=4, signed int

* fix lint

* add ic_bn % 4 checker in schedule

There are dependencies on dmlc-core in TVM public API headers
(e.g. some headers include dmlc/logging.h) so it needs to be installed
as part of TVM for TVM headers to be actually usable.

* Fix parser

* Doc fix

* Add module utility functions necessary for prelude

* Implement prelude in text format

* Remove programmatically constructed prelude defs

* Fix 0-arity type conses in pretty printer and test

* Make prelude loading backwards-compatible

* Fix patterns

* Improve some prelude defs

* Fix `ImportFromStd`

It needs to also follow the "add unchecked, add checked" pattern

* Lint roller

* Woops

* Address feedback

* Fix `test_list_constructor` VM test

* Fix `test_adt.py` failures

please see https://stackoverflow.com/a/26949099

* [AUTOTVM][DOCS] Add a link to autoTVM tutorial to direct the details of building NN with relay

* [AUTOTVM][DOCS] Add a link to autoTVM tutorial to direct the details of building NN with relay

* [Fix] Add more pad_mode support for onnx converter

* robustness fix

Add different batch sizes and channel numbers to
MXNet Convolution and Deconvolution tests.