Switch to toybox gzip.

(Although I was the one who added the gzcat reference, I don't believe
we actually use it. And neither my Debian host nor toybox has gzcat --
as opposed to zcat -- anyway. So just quietly drop that.)

Test: treehugger
Change-Id: I95d94dab1daf72faedfa170770e8ebfaa37b70c6
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index 711a9c7..ee6e9dc 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -82,8 +82,6 @@
 	"fuser":    Allowed,
 	"getopt":   Allowed,
 	"git":      Allowed,
-	"gzcat":    Allowed,
-	"gzip":     Allowed,
 	"hexdump":  Allowed,
 	"jar":      Allowed,
 	"java":     Allowed,