Makefile: blacklisted mtree module from compilation

- it requires backports from sr branch (shm_initialized())

Makefile

@@ -222,6 +222,8 @@ else
 	# excluded because they do not compile (remove them only after they are
 	#  fixed) -- andrei
 	exclude_modules+= bdb dbtext iptrtpproxy pa rls
+	# dcm: for now needs backports from sr
+	exclude_modules+= mtree
 endif
 
 # always exclude the CVS dir