patch 8.0.1060: when imstyle is one, mapping <Left> breaks preediting

Problem:    When imstyle is one, mapping <Left> breaks preediting.
Solution:   Pass though preediting key-events. (Yasuhiro Matsumoto, closes
            #2064, closes #2063)
diff --git a/src/mbyte.c b/src/mbyte.c
index 617a97d..f279bde 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -4964,7 +4964,11 @@
 	return;
     }
 
-    if (State & NORMAL)
+    if (State & NORMAL
+#ifdef FEAT_TERMINAL
+	    && !term_use_loop()
+#endif
+       )
     {
 	im_preedit_cursor = 0;
 	return;