Fix bug in ParGridFunction::ProjectDiscCoefficient
Fix bug in ParGridFunction::ProjectDiscCoefficient

Calling parallel assemble is conceptually wrong, since a GridFunction
represents also vdofs. See https://github.com/mfem/mfem/issues/443

Suggested-by: Veselin Dobrev <9bcf736b3ca8d43afd6f62f1bbc3521ab0181e43@llnl.gov>

mfem/mfem,mfem/mfem,mfem/mfem,mfem/mfem,mfem/mfem