lineedit: fix trivial build failure

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index b168f1b..8564307 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -1255,7 +1255,9 @@
 {
 	line_input_t *n = xzalloc(sizeof(*n));
 	n->flags = flags;
+#if MAX_HISTORY > 0
 	n->max_history = MAX_HISTORY;
+#endif
 	return n;
 }