add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/tools/build/feature/test-reallocarray.c
..
..
@@ -6,3 +6,5 @@
6
6
 {
7
7
 	return !!reallocarray(NULL, 1, 1);
8
8
 }
9
+
10
+#undef _GNU_SOURCE