findutils: plug a memory leak (close #22857)

Using the upstream patch directly.  It's copied in nixpkgs, because:
 - fetchpatch isn't usable at this point in bootstrapping,
 - the upstream patch creates collisions in NEWS.

pkgs/tools/misc/findutils/default.nix

@@ -8,7 +8,9 @@ stdenv.mkDerivation rec {
     sha256 = "178nn4dl7wbcw499czikirnkniwnx36argdnqgz4ik9i6zvwkm6y";
   };
 
-  nativeBuildInputs = [ coreutils ];
+  patches = [ ./memory-leak.patch ];
+
+  buildInputs = [ coreutils ]; # bin/updatedb script needs to call sort
 
   doCheck = !stdenv.isDarwin;
 

pkgs/tools/misc/findutils/memory-leak.patch

@@ -0,0 +1,21 @@
+http://git.savannah.gnu.org/cgit/findutils.git/patch/?id=c1556892a
+diff --git a/find/fstype.c b/find/fstype.c
+index 535f920..a0ac8bc 100644
+--- a/find/fstype.c
++++ b/find/fstype.c
+@@ -75,14 +75,7 @@ free_file_system_list (struct mount_entry *p)
+   while (p)
+     {
+       struct mount_entry *pnext = p->me_next;
+-
+-      free (p->me_devname);
+-      free (p->me_mountdir);
+-
+-      if (p->me_type_malloced)
+-	free (p->me_type);
+-      p->me_next = NULL;
+-      free (p);
++      free_mount_entry (p);
+       p = pnext;
+     }
+ }