ENH: specialise bitOr<unsigned char> reduction

STYLE: remove extraneous parRun check before Pstream::combineReduce

- already handled by Pstream::combineReduce itself

STYLE: remove deprecated globalMeshData::ListPlusEqOp

- deprecated/superseded by ListOps::appendEqOp (2020-09)

STYLE: qualify stream format with IOstreamOption (easier to find)

src/functionObjects/utilities/areaWrite/areaWriteImpl.C

@@ -74,10 +74,7 @@ void Foam::areaWrite::performAction
         fieldNames = areaMesh.thisDb().names<GeoField>(fieldSelection_);
 
         // Synchronize names
-        if (Pstream::parRun())
-        {
-            Pstream::combineReduce(fieldNames, ListOps::uniqueEqOp<word>());
-        }
+        Pstream::combineReduce(fieldNames, ListOps::uniqueEqOp<word>());
         Foam::sort(fieldNames);  // Consistent order
     }