mtools: needs mmu

Fixes:
http://autobuild.buildroot.net/results/915/91531e06646b7453248be5c7ca22101edd42d641/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/mtools/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_MTOOLS
 	bool "mtools"
 	depends on BR2_USE_WCHAR
+	depends on BR2_USE_MMU # fork()
 	help
 	  Mtools is a collection of utilities to access MS-DOS disks from
 	  Unix without mounting them. It supports Win'95 style long file