Expand co_broadcast test coverage for derived type arguments; remove temporary diagnostic output

[rouson]

coverage on master

Summary of changes

1. Add one new co_broadcast test with a derived-type argument with allocatable components.
2. Enhance a co_broadcast test to cover more types, component attributes (pointer) and type relationships (extend).
3. Remove a diagnostic print statement that was presumably inserted into mpi_caf.c temporarily.

Rationale for changes

@afanfa has committed support co_broadcast with derived type actual arguments to the gfortran trunk (10.0.0). All work on this branch has been completed and the branch can now be merged and deleted.

Additional info and certifications

This pull request (PR) is a:

• Bug fix
• Feature addition
• Other, Please describe: add/enhance tests; remove unnecessary output

I certify that

• I certify that:
  • I have reviewed and followed the contributing guidelines
  • I will wait at least 24 hours before self-approving the PR to give another
    OpenCoarrays developer a chance to review my proposed code
  • I have not introduced errant white space (no trailing white space or white space errors may
    be introduced)
  • I have added an explanation of what these changes do and why they should be included
  • I have checked to ensure there aren't other open Pull Requests for the same change
  • I have you written new tests for these changes
  • I have successfully tested these changes locally
  • I have commented any non-trivial, non-obvious code changes
  • The commits are logically atomic, self consistent and coherent
  • The commit messages follow best practices
  • Test coverage is maintained or increased after this is merged

Code coverage data

[codecov]

Codecov Report

Merging #684 into master will decrease coverage by 2.54%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #684      +/-   ##
==========================================
- Coverage   57.07%   54.53%   -2.55%     
==========================================
  Files           4        3       -1     
  Lines        3222     2923     -299     
==========================================
- Hits         1839     1594     -245     
+ Misses       1383     1329      -54