fix: don't use DEPENDS with add_custom_command(TARGET)

[kou]

Release Summary:

Resolved issues:

resolves #5073

Description of changes:

We can use DEPENDS for add_custom_command(OUTPUT) but can't use DEPENDS for add_custom_command(TARGET).

See also the add_custom_command(TARGET) document:
https://cmake.org/cmake/help/latest/command/add_custom_command.html#build-events

If we use DEPENDS for add_custom_command(TARGET), the following warning is reported:

The following keywords are not supported when using
add_custom_command(TARGET): DEPENDS.

We can just remove DEPENDS to suppress the warning.

Call-outs:

Address any potentially confusing code. Is there code added that needs to be cleaned up later? Is there code that is missing because it’s still in development? If a callout is specific to a section of code, it might make more sense to leave a comment on your own PR file diff.

Testing:

How is this change tested (unit tests, fuzz tests, etc.)? What manual testing was performed? Are there any testing steps to be verified by the reviewer?

cmake -DS2N_INTERN_LIBCRYPTO=ON doesn't report the warning with this.

How can you convince your reviewers that this PR is safe and effective?

This just removes the warned and ignored argument.

Is this a refactor change? If so, how have you proved that the intended behavior hasn't changed?

No.

Remember:

• Any change to the library source code should at least include unit tests.
• Any change to the core stuffer or blob methods should include CBMC proofs.
• Any change to the CI or tests should:
  1. prove that the test succeeds for good input
  2. prove that the test fails for bad input (eg, a test for memory leaks fails when a memory leak is committed)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[goatgoose]

Thanks for fixing this!