bmon: needs mmu

Fixes
http://autobuild.buildroot.net/results/673b0e9a1ba75123ba2c59df8ad81550170fffef

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/bmon/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_BMON
 	bool "bmon"
 	depends on BR2_INET_IPV6
+	depends on BR2_USE_MMU # fork()
 	help
 	  Linux bandwidth monitor