duma: not available on non-MMU platforms

By design, building duma on Blackfin and other non-MMU platforms is
quite useless: it uses page mappings to detect buffer overrun and
use-after-free programming errors. Therefore, this commit simply marks
duma as not available on non-MMU platforms.

Fixes:

  http://autobuild.buildroot.org/results/951/9519d7abb45c6a789874ec6bb84418c31a98916b/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/duma/Config.in

@@ -2,6 +2,10 @@ config BR2_PACKAGE_DUMA
 	bool "duma"
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_TOOLCHAIN_HAS_THREADS
+	# By design, duma uses page mapping to isolate
+	# allocations. Non-MMU platforms cannot perform such
+	# things.
+	depends on BR2_USE_MMU
 	help
 	  D.U.M.A. - Detect Unintended Memory Access. A fork of the
 	  Electric Fence library. Detects buffer overflow and
@@ -17,4 +21,5 @@ config BR2_PACKAGE_DUMA_NO_LEAKDETECTION
 endif # BR2_PACKAGE_DUMA
 
 comment "duma needs a toolchain w/ C++, threads"
+	depends on BR2_USE_MMU
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_HAS_THREADS