ms-sys: avoid the build timestamp from leaking into the manpage

Also proposed upstream as https://sourceforge.net/p/ms-sys/patches/8/

pkgs/tools/misc/ms-sys/default.nix

@@ -8,6 +8,8 @@ stdenv.mkDerivation rec {
     url = "mirror://sourceforge/ms-sys/${pname}-${version}.tar.gz";
     sha256 = "06xqpm2s9cg8fj7a1822wmh3p4arii0sifssazg1gr6i7xg7kbjz";
   };
+  # TODO: Remove with next release, see https://sourceforge.net/p/ms-sys/patches/8/
+  patches = [ ./manpages-without-build-timestamps.patch ];
 
   nativeBuildInputs = [ gettext ];
 

pkgs/tools/misc/ms-sys/manpages-without-build-timestamps.patch

@@ -0,0 +1,12 @@
+diff -u ms-sys-2.6.0/Makefile ms-sys-2.6.0-fixed/Makefile
+--- ms-sys-2.6.0/Makefile	2015-09-27 20:39:45.000000000 +0200
++++ ms-sys-2.6.0-fixed/Makefile2020-01-06 16:43:55.181477511 +0100
+@@ -121,7 +121,7 @@
+
+ $(DESTDIR)$(MANDIR)/%: $(MAN)/$(dir $(*D))/$(*F)
+ 	install -D -m 644 $(MAN)/$(dir $(*D))$(*F) $@
+-	gzip -f $@
++	gzip -n -f $@
+
+ #$(DESTDIR)$(MANDIR)/%: $(MAN)/$(*F)
+ #	echo t: $<