blktrace: needs MMU support

iowatcher/main.c uses system() which uses fork().

Signed-off-by: Rahul Bedarkar <rahul.bedarkar@imgtec.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/blktrace/Config.in

@@ -2,6 +2,7 @@ config BR2_PACKAGE_BLKTRACE
 	bool "blktrace"
 	depends on BR2_PACKAGE_LIBAIO_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_HAS_THREADS_NPTL # clock_nanosleep()
+	depends on BR2_USE_MMU # system()
 	select BR2_PACKAGE_LIBAIO
 	help
 	  blktrace is a block layer IO tracing mechanism which provides
@@ -11,5 +12,6 @@ config BR2_PACKAGE_BLKTRACE
 	  http://git.kernel.dk/?p=blktrace.git;a=summary
 
 comment "blktrace needs a toolchain w/ NPTL"
+	depends on BR2_USE_MMU
 	depends on BR2_PACKAGE_LIBAIO_ARCH_SUPPORTS
 	depends on !BR2_TOOLCHAIN_HAS_THREADS_NPTL