Fixes #402, #403.

JPEG-2000 (JPC) Decoder:
- Added the setting of several pointers to null in some cleanup code
  after the pointed-to memory was freed.  This pointer nulling is not
  needed normally, but it is needed when certain debugging logs are
  enabled (so that the debug code understands that the memory associated
  with the aforementioned pointers has been freed).

Author: mdadams

data/test/bad/poc_402.jpc

@@ -1136,23 +1136,23 @@ static int jpc_dec_tilefini(jpc_dec_t *dec, jpc_dec_tile_t *tile)
 
 	if (tile->cp) {
 		jpc_dec_cp_destroy(tile->cp);
-		//tile->cp = 0;
+		tile->cp = 0;
 	}
 	if (tile->tcomps) {
 		jas_free(tile->tcomps);
-		//tile->tcomps = 0;
+		tile->tcomps = 0;
 	}
 	if (tile->pi) {
 		jpc_pi_destroy(tile->pi);
-		//tile->pi = 0;
+		tile->pi = 0;
 	}
 	if (tile->pkthdrstream) {
 		jas_stream_close(tile->pkthdrstream);
-		//tile->pkthdrstream = 0;
+		tile->pkthdrstream = 0;
 	}
 	if (tile->pptstab) {
 		jpc_ppxstab_destroy(tile->pptstab);
-		//tile->pptstab = 0;
+		tile->pptstab = 0;
 	}
 
 	tile->state = JPC_TILE_DONE;
@@ -2288,6 +2288,9 @@ static int jpc_dec_dump(const jpc_dec_t *dec)
 	const jpc_dec_tile_t *tile;
 	for (tileno = 0, tile = dec->tiles; tileno < dec->numtiles;
 	  ++tileno, ++tile) {
+		if (!tile->tcomps) {
+			continue;
+		}
 		assert(!dec->numcomps || tile->tcomps);
 		unsigned compno;
 		const jpc_dec_tcomp_t *tcomp;