Disallow system m4

Everything should be using the prebuilt now.

Bug: 117561006
Test: treehugger
Test: check bass logs for m4 uses
Change-Id: Ic69d715d72d64bb0082e2f2c247113155d8b3de0
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index fcc4309..184e6f1 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -94,7 +94,6 @@
 	"java":     Allowed,
 	"javap":    Allowed,
 	"lsof":     Allowed,
-	"m4":       Log,
 	"openssl":  Allowed,
 	"patch":    Allowed,
 	"pstree":   Allowed,