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_dbuffer.c

@@ -20,10 +20,9 @@
 #include "pio_util.h"
 
 int
-cdiPioDbufferInit(struct dBuffer **dbuffer, size_t bufSize)
+cdiPioDbufferInit(struct dBuffer *db, size_t bufSize)
 {
-  assert(dbuffer);
-  struct dBuffer *db = *dbuffer = (struct dBuffer *) Malloc(sizeof(*db));
+  assert(db);
   db->wr_pointer = 0;
 
 #ifndef _SX
@@ -62,14 +61,9 @@ cdiPioDbufferInit(struct dBuffer **dbuffer, size_t bufSize)
 }
 
 void
-cdiPioDbufferDestroy(struct dBuffer **dbuffer)
+cdiPioDbufferDestroy(struct dBuffer *db)
 {
-  struct dBuffer *db = *dbuffer;
-
   free(db->buffer);
-  Free(db);
-
-  return;
 }
 
 static size_t