[svn-r8853] Purpose:

Code optimization

Description:
    Refactor B-tree code to extract all common information for a B-tree into a
shared structure that is pointed to by all the nodes in tree (instead of being
included in each node).

    Also re-order B-tree node comparison checks for chunked datasets to
check for >= the upper node first, since the comparison is a bit "heavy" and
this check is more likely to succeed when you are adding records to the
dataset.

Platforms tested:
    Solaris 2.7 (arabica)
    FreeBSD 4.10 (sleipnir) w/parallel
    Too minor to require h5committest
    (also, recent h5dump commits have broken testing...)

src/H5Fpkg.h

@@ -127,7 +127,7 @@ typedef struct H5F_file_t {
     struct H5HG_heap_t **cwfs;	/* Global heap cache			*/
     H5FO_t *open_objs;          /* Open objects in file                 */
     H5F_close_degree_t fc_degree;   /* File close behavior degree	*/
-    H5RC_t      *rc_page;       /* Pointer to ref-counted raw B-tree node buffer    */
+    H5RC_t *grp_btree_shared;   /* Ref-counted group B-tree node info   */
 } H5F_file_t;
 
 /* A record of the mount table */