BUG/MEDIUM: htx: fix typo in htx_replace_stline() making it fail all the time

A typo in the block type check makes this function fail all the time,
which has impact on anything rewriting a start line (set-uri, set-path
etc).

No backport needed.
diff --git a/src/htx.c b/src/htx.c
index 2c660e7..cd16bf3 100644
--- a/src/htx.c
+++ b/src/htx.c
@@ -602,7 +602,7 @@
 	uint32_t size;
 
 	type = htx_get_blk_type(blk);
-	if (type != HTX_BLK_REQ_SL || HTX_BLK_RES_SL)
+	if (type != HTX_BLK_REQ_SL && type != HTX_BLK_RES_SL)
 		return NULL;
 
 	/* Save start-line info and flags */