Invert logic of ternary pointer checks

Invert logic of ternary pointer checks

A PGI compiler warning is triggered by expressions like

  ptr == NULL ? NULL : ptr

that the PGI compiler handles incorrectly.  It chooses the pointer type
of the first option (void*) and warns about conversion of the second
without a cast.  Flip the expression logic to

  ptr != NULL ? ptr : NULL

to help the compiler choose the proper result type.