Changed unpack start pointer (from_ptr) setup.

- Testsuite found as this was set to NULL until a pack to catch invalid unpacks
     that if a realloc occured on the first pack, then all ptrs updated by
     relative amounts and then the from_ptr was not NULL and not set on
	 first pack correctly. Have changed it to the simple method.

This commit was SVN r2098.

src/util/pack.c

@@ -121,7 +121,7 @@ size_t isize = 0;
 	bptr->base_ptr = (void*) malloc (isize); 
 
 	bptr->data_ptr = bptr->base_ptr; /* set the start of the buffer */
-	/* leave from_ptr NULL so we catch an unpack before pack! */
+	bptr->from_ptr = bptr->base_ptr; /* set the unpack start at start */
 
 	/* set counts for size and space */
 	bptr->size = bptr->space = isize;
@@ -366,9 +366,6 @@ return (OMPI_SUCCESS);
 
     bptr->space -= op_size;
 
-    /* if first pack also set the from_ptr as it is now valid */
-    if (!bptr->from_ptr) bptr->from_ptr = bptr->base_ptr;
-
     return OMPI_SUCCESS;
 }