This partly re-applies 5ae025b56a with the
following changes:
- Use path-constant to deduce the path relative to the point of execution
rather than the Jamfile.
- Use that path only to list source files to be passed to Doxygen.
- Keep the project rule, but remove the duplicate requirements that are
explicitly specified in standalone_main.
Hopefully, this should work around the problem of Reference generation
in the official docs.
Andrey Semashev
9d1284ef6d
