patch 8.2.4177: Vim9: autoload script not loaded after "vim9script noclear"

Problem:    Vim9: autoload script not loaded after "vim9script noclear".
Solution:   Check IMP_FLAGS_AUTOLOAD properly.
diff --git a/src/vim9compile.c b/src/vim9compile.c
index ddb486b..2b706ad 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -621,12 +621,12 @@
     if (ret == NULL)
 	ret = find_imported_in_script(name, len, current_sctx.sc_sid);
 
-    if (ret != NULL && load && ret->imp_flags == IMP_FLAGS_AUTOLOAD)
+    if (ret != NULL && load && (ret->imp_flags & IMP_FLAGS_AUTOLOAD))
     {
 	scid_T dummy;
 
 	// script found before but not loaded yet
-	ret->imp_flags = 0;
+	ret->imp_flags &= ~IMP_FLAGS_AUTOLOAD;
 	(void)do_source(SCRIPT_ITEM(ret->imp_sid)->sn_name, FALSE,
 							    DOSO_NONE, &dummy);
     }