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)

src/getchar.c

@@ -1598,8 +1598,13 @@ vgetc(void)
       {
 	int did_inc = FALSE;
 
-	if (mod_mask)		/* no mapping after modifier has been read */
+	if (mod_mask
+#if defined(FEAT_XIM) && defined(FEAT_GUI_GTK)
+	    || im_is_preediting()
+#endif
+		)
 	{
+	    /* no mapping after modifier has been read */
 	    ++no_mapping;
 	    ++allow_keys;
 	    did_inc = TRUE;	/* mod_mask may change value */

src/mbyte.c

@@ -4964,7 +4964,11 @@ im_delete_preedit(void)
 	return;
     }
 
-    if (State & NORMAL)
+    if (State & NORMAL
+#ifdef FEAT_TERMINAL
+	    && !term_use_loop()
+#endif
+       )
     {
 	im_preedit_cursor = 0;
 	return;

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1060,
 /**/
     1059,
 /**/