CID 356082: Memory - corruptions in lib/dns/rbtdb.c

Updated Coverity Scan identified the following issue:

*** CID 356082:  Memory - corruptions  (OVERRUN)
/lib/dns/rbtdb.c: 9513 in rehash_gluetable()
9507     
9508     	newbits = rehash_bits(version, version->glue_table_nodecount);
9509     	newsize = ISC_HASHSIZE(newbits) * sizeof(version->glue_table[0]);
9510     
9511     	version->glue_table = isc_mem_get(version->rbtdb->common.mctx, newsize);
9512     	version->glue_table_bits = newbits;
>>>     CID 356082:  Memory - corruptions  (OVERRUN)
>>>     Calling "memset" with "version->glue_table" and "newsize" is suspicious because of the very large index, 68719476736. The index may be due to a negative parameter being interpreted as unsigned. [Note: The source code implementation of the function has been overridden by a builtin model.]
9513     	memset(version->glue_table, 0, newsize);
9514     
9515     	for (i = 0; i < oldcount; i++) {
9516     		rbtdb_glue_table_node_t *gluenode;
9517     		rbtdb_glue_table_node_t *nextgluenode;
9518     		for (gluenode = oldtable[i]; gluenode != NULL;