Licensing of Windows test functions taken from Ruby source

[maxirmx]

Windows version of libdwarfs uses for tests functions taken from original Ruby source.
This code is now placed in disorder to a single file: rb_w32-tebako-tests-mocks.c

In the original Ruby source the code that I took is tagged partially with

/* License: Ruby's */

and partially with

/* License: Artistic or GPL */

Shall we add anything to our license ? Adopted code is used to testing only.

[ronaldtse]

I think it’s fine to keep the tests, and we have to describe the licenses properly. However, we must not distribute the tests with the gem.

To that, let’s add a test so that we don’t distribute these tests.

[ronaldtse]

@maxirmx maybe we can get someone to rewrite the tests. Where are they now?

[maxirmx]

• On Windows Ruby implements its own file IO layer that has POSIX signatures but different function names
• Tebako patches calls to these Ruby functions
  For example
  On *nix tebako replaces a call to access with a call to tebako_access
  On Windows Ruby implements rb_w32_access with access signature. Tebako replaces a call to rb_w32_access with a call to tebako_access
• In order to test patching of calls to Windows-specific functions like rb_w32_access we have mocks in https://github.com/tamatebako/libdwarfs/blob/main/tests/rb_w32-tebako-tests-mocks.c
• Some code for the mocks was directly taken from Ruby source distributed under "Ruby's" licence which is GNU or Artistics license