* builds/windows/detect.mk (COPY): Make it work with `shell`.

Without this patch, we get the error

  builds/toplevel.mk:127: *** missing separator.  Stop.

Reported by Anuj, with a solution from Alexei.
diff --git a/ChangeLog b/ChangeLog
index 116c526..6cc94fd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,16 @@
+2020-12-23  Werner Lemberg  <wl@gnu.org>
+
+	* builds/windows/detect.mk (COPY): Make it work with `shell`.
+
+	Without this patch, we get the error
+
+	  builds/toplevel.mk:127: *** missing separator.  Stop.
+
+	Reported by Anuj, with a solution from Alexei.
+
 2020-12-23  Ignacio Casal Quinteiro  <qignacio@amazon.com>
 
-	meson.build (ft2_defines): Fix builds on Windows.
+	* meson.build (ft2_defines): Fix builds on Windows.
 
 2020-12-18  Tatsuyuki Ishi  <ishitatsuyuki@gmail.com>
 
diff --git a/builds/windows/detect.mk b/builds/windows/detect.mk
index 303dc8b..a079f91 100644
--- a/builds/windows/detect.mk
+++ b/builds/windows/detect.mk
@@ -81,9 +81,9 @@
   # (2004-11-11), and then in the devel mailing list (2004-11-20 to -23).
   #
   ifeq ($(OS),Windows_NT)
-    COPY := cmd.exe /c copy
+    COPY := >nul cmd.exe /c copy
   else
-    COPY := copy
+    COPY := >nul copy
   endif  # test NT