The upcoming transition to GPR2 for the C/Python APIs will reveal
complaints about missing source directories. This is a good improvement,
but not the point of these testcases, so adjust them so that source
directories are not missing.
In particular for aggregate projects, it is sometimes necessary to
restrict the analysis to a sub-project in a GPR project tree. Similarly
to the project-based unit provider, add a Project/Project_Name argument
to the subprograms that collect preprocessor-related compilation options
in project files to restrict their analysis to a sub-project.
TN: V708-022
