[svn-r12770] Description:

Overhaul usage of object header chunks to reduce I/O operations and
memory allocations.  The object header prefix is now stored in the first
object header chunk's "image" in memory.

    Also, lots of formatting cleanups.

    Taught h5debug tool about new object header format (which isn't enabled
just yet).

Tested on:
    Linux/32 2.6 (chicago)
    Linux/64 2.6 (chicago2)

tools/misc/h5debug.c

@@ -380,9 +380,16 @@ main(int argc, char *argv[])
 
         status = H5FS_sects_debug(f, H5P_DATASET_XFER_DEFAULT, addr, stdout, 0, VCOL, extra, extra2);
 
+    } else if(!HDmemcmp(sig, H5O_HDR_MAGIC, H5O_SIZEOF_MAGIC)) {
+        /*
+         * Debug v2 object header (which have signatures).
+         */
+
+        status = H5O_debug(f, H5P_DATASET_XFER_DEFAULT, addr, stdout, 0, VCOL);
+
     } else if(sig[0] == H5O_VERSION_1) {
         /*
-         * This could be an object header.  Since they don't have a signature
+         * This could be a v1 object header.  Since they don't have a signature
          * it's a somewhat "ify" detection.
          */
         status = H5O_debug(f, H5P_DATASET_XFER_DEFAULT, addr, stdout, 0, VCOL);