add wmake rules for PGI compiler

@Roger

In some third-party places it could be that the WM_CC, WM_CXX variables are not properly exported for autoconfig (needs investigation). In that case, can also handle manually and explicitly. For example,

./makeOPENMPI -- CC=pgcc

mentioned in commit 22c30c465aa425f814f8cb9d05874d56f5e68b7e

made the issue visible to everyone

closed