Fix remaining references to "substitute-binary".

* nix/nix-daemon/guix-daemon.cc (main): Change substitute-binary to
  substitute.
* po/guix/POTFILES.in: Likewise.
* tests/guix-daemon.sh: Likewise.
* tests/guix-system.sh: Likewise.

nix/nix-daemon/guix-daemon.cc

@@ -310,7 +310,7 @@ main (int argc, char *argv[])
 	  if (subs == "default")
 	    {
 	      string subst =
-		settings.nixLibexecDir + "/guix/substitute-binary";
+		settings.nixLibexecDir + "/guix/substitute";
 	      setenv ("NIX_SUBSTITUTERS", subst.c_str (), 1);
 	    }
 	}

po/guix/POTFILES.in

@@ -9,7 +9,7 @@ guix/scripts/package.scm
 guix/scripts/gc.scm
 guix/scripts/hash.scm
 guix/scripts/pull.scm
-guix/scripts/substitute-binary.scm
+guix/scripts/substitute.scm
 guix/scripts/authenticate.scm
 guix/scripts/system.scm
 guix/scripts/lint.scm

tests/guix-daemon.sh

@@ -17,7 +17,7 @@
 # along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 #
-# Test the daemon and its interaction with 'guix substitute-binary'.
+# Test the daemon and its interaction with 'guix substitute'.
 #
 
 set -e
@@ -51,7 +51,7 @@ Deriver: $drv
 EOF
 
 # Remove the cached narinfo.
-rm -f "$XDG_CACHE_HOME/guix/substitute-binary/$hash_part"
+rm -f "$XDG_CACHE_HOME/guix/substitute/$hash_part"
 
 # Make sure we see the substitute.
 guile -c '

tests/guix-system.sh

@@ -17,7 +17,7 @@
 # along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 #
-# Test the daemon and its interaction with 'guix substitute-binary'.
+# Test the daemon and its interaction with 'guix substitute'.
 #
 
 set -e