ASN.1 print fix.

When printing out an ASN.1 structure, if the type is an item template don't
fall through and attempt to interpret as a primitive type.

(Imported from upstream's 5dc1247a7494f50c88ce7492518bbe0ce6f124fa.)

Change-Id: Ica39757792cbf3f83879953b67838927ddbdb809
Reviewed-on: https://boringssl-review.googlesource.com/4009
Reviewed-by: Adam Langley <agl@google.com>

crypto/asn1/tasn_prn.c

@@ -229,6 +229,7 @@ static int asn1_item_print_ctx(BIO *out, ASN1_VALUE **fld, int indent,
 			if (!asn1_template_print_ctx(out, fld, indent,
 							it->templates, pctx))
 				return 0;
+			break;
 			}
 		/* fall thru */
 		case ASN1_ITYPE_MSTRING: