Fix leak introduced in 25cecd701
Fix leak introduced in 25cecd701

Notes:
* This was only discovered by running Valgrind, which is something we
  don't normally do on libMesh PRs
* I think it's unnecessary to check if (_pc) here as it is never
  explicitly set to nullptr in the code, but I left it in to mimic the
  previous behavior for now.

libMesh/libmesh,libMesh/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,libMesh/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,BalticPinguin/libmesh,BalticPinguin/libmesh,libMesh/libmesh,dschwen/libmesh,libMesh/libmesh,libMesh/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,jwpeterson/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,BalticPinguin/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,libMesh/libmesh,BalticPinguin/libmesh,dschwen/libmesh,libMesh/libmesh