atf: needs mmu

Fixes:
http://autobuild.buildroot.net/results/950/95069436dd5b2004e59851b8c731d534b86062a5/

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

package/atf/Config.in

@@ -1,6 +1,7 @@
 config BR2_PACKAGE_ATF
 	bool "atf"
 	depends on BR2_INSTALL_LIBSTDCPP
+	depends on BR2_USE_MMU # fork()
 	help
 	  ATF, or Automated Testing Framework, is a collection of
 	  libraries to write test programs in C, C++ and POSIX shell.
@@ -9,3 +10,4 @@ config BR2_PACKAGE_ATF
 
 comment "atf needs a toolchain w/ C++"
 	depends on !BR2_INSTALL_LIBSTDCPP
+	depends on BR2_USE_MMU