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/Makefile.am

@@ -232,6 +232,7 @@ libcdipio_la_SOURCES =							\
 	pio_dbuffer.c							\
 	pio_dbuffer.h							\
 	pio_dist_grid.c							\
+	pio_dist_grid.h							\
 	pio_idxlist_cache.c						\
 	pio_idxlist_cache.h						\
 	pio_id_set.h							\