Consolidation with CDI-PIO (develop)

Generally, this is !11 (merged) rebased onto the develop branch.

This is the first develop-based version accepted by the Buildbot of ICON: https://buildbot.dkrz.de/grid?branch=m300488/cdi-pio-2-integration

src/pio_server.c

@@ -466,8 +466,7 @@ writeNetCDFStreamParallel(size_t streamIdx, struct streamMapping *mapping, doubl
   const int streamID = openStreams.entries[streamIdx], vlistID = streamInqVlist(streamID);
   const MPI_Comm collComm = commInqCommColl();
   // init redistCache if applicable
-  const bool reuseRedists
-      = conf->cacheRedists != 0 ? handleRedistCache(streamIdx, mapping, (size_t) nvars, vlistID, collComm) : false;
+  const bool reuseRedists = conf->cacheRedists ? handleRedistCache(streamIdx, mapping, (size_t) nvars, vlistID, collComm) : false;
   struct cacheRedist *restrict retained = rxWin[streamIdx].retained;
 
   for (int varID = 0; varID < nvars; ++varID)