Move mktemp(1) to toybox.

Test: clean build
Change-Id: I7b02c7ee8dafb504c90d3af63698a09627556947
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index adcc766..fdd291e 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -97,7 +97,6 @@
 	"lsof":      Allowed,
 	"m4":        Allowed,
 	"md5sum":    Allowed,
-	"mktemp":    Allowed,
 	"mv":        Allowed,
 	"openssl":   Allowed,
 	"patch":     Allowed,
@@ -161,6 +160,7 @@
 	"ln":       Toybox,
 	"ls":       Toybox,
 	"mkdir":    Toybox,
+	"mktemp":   Toybox,
 	"od":       Toybox,
 	"paste":    Toybox,
 	"pwd":      Toybox,