[CMake][OpenCL] Remove warning for OpenCL wrapper

[Lunderberg]

Previously, setting set(USE_OPENCL ON) would result in a warning, stating that the runtime wrapper for OpenCL would be used. Since this is the desired behavior when OpenCL support is enabled, and is not something that a user should fix, this commit removes the warning.

[tvm-bot]

Thanks for contributing to TVM! Please refer to the contributing guidelines https://tvm.apache.org/docs/contribute/ for useful information and tips. Please request code reviews from Reviewers by @-ing them in a comment.

• cc @echuraev, @elvin-n _{See #10317 for details}

_{Generated by tvm-bot}

[tvm-bot]

Thanks for contributing to TVM! Please refer to the contributing guidelines https://tvm.apache.org/docs/contribute/ for useful information and tips. Please request code reviews from Reviewers by @-ing them in a comment.

• cc @echuraev, @elvin-n _{See #10317 for details}

_{Generated by tvm-bot}

[Lunderberg]

@tvm-bot rerun

[echuraev]

I have added this warning message especially to notify the user that the OpenCL wrapper will be used, and it might lead to a runtime error if the OpenCL library doesn't exist on a target device.
If warning message might embarrass, let's keep just status message?

[Lunderberg]

I have added this warning message especially to notify the user that the OpenCL wrapper will be used, and it might lead to a runtime error if the OpenCL library doesn't exist on a target device.

Good point, as that is a runtime error that would occur on first usage, whereas all the other library dependencies would cause a failure when importing libtvm_runtime.so.

If warning message might embarrass, let's keep just status message?

I like this idea, and have the message back in, but with message(STATUS ...) instead of message(WARNING ...). I also adjusted the wording of the message to make it clear what the wrapper does (runtime search for library) and not just that a wrapper exists. Could you check that the updated wording is accurate?

[echuraev]

LGTM. Thanks!