patch 8.2.1166: once mouse move events are enabled getchar() returns them

Problem:    Once mouse move events are enabled getchar() returns them.
Solution:   Ignore K_MOUSEMOVE in getchar(). (closes #6424)
diff --git a/src/getchar.c b/src/getchar.c
index 2beffa5..e040748 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -1501,7 +1501,7 @@
 	{
 	    update_topline_cursor();	// update cursor position and topline
 	    normal_cmd(&oa, FALSE);	// execute one command
-	    vpeekc();			// check for end of file
+	    (void)vpeekc();		// check for end of file
 	}
 	while (scriptin[oldcurscript] != NULL);
 
@@ -2045,7 +2045,7 @@
 	    // getchar(0) and char avail: return char
 	    n = plain_vgetc();
 
-	if (n == K_IGNORE)
+	if (n == K_IGNORE || n == K_MOUSEMOVE)
 	    continue;
 	break;
     }