Switch cp(1) to toybox.

Test: treehugger
Change-Id: I908e1d6aa2aa7016432ac7ff4abc56e8163bad8a
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index b50748b..17decd0 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -78,7 +78,6 @@
 	"bash":      Allowed,
 	"bc":        Allowed,
 	"bzip2":     Allowed,
-	"cp":        Allowed,
 	"date":      Allowed,
 	"dd":        Allowed,
 	"diff":      Allowed,
@@ -132,6 +131,7 @@
 	"cat":       Toybox,
 	"chmod":     Toybox,
 	"cmp":       Toybox,
+	"cp":        Toybox,
 	"comm":      Toybox,
 	"cut":       Toybox,
 	"dirname":   Toybox,