Move dirname(1) to toybox.

Test: treehugger
Change-Id: Ie1ffbfb900803940620dd11a7ed6bfda76bee86c
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index 12daee3..623b3c9 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -84,7 +84,6 @@
 	"date":      Allowed,
 	"dd":        Allowed,
 	"diff":      Allowed,
-	"dirname":   Allowed,
 	"du":        Allowed,
 	"echo":      Allowed,
 	"egrep":     Allowed,
@@ -161,6 +160,7 @@
 	"cat":      Toybox,
 	"cmp":      Toybox,
 	"comm":     Toybox,
+	"dirname":  Toybox,
 	"env":      Toybox,
 	"id":       Toybox,
 	"od":       Toybox,