flann: disable with the problematic NIOS II toolchain

Fixes:

  http://autobuild.buildroot.org/results/062/0620bf8d60aa57949cede0c5b3920ef5446fe98b/

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

package/flann/Config.in

@@ -2,6 +2,8 @@ config BR2_PACKAGE_FLANN
 	bool "flann"
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on !BR2_PREFER_STATIC_LIB
+	# triggers an assert in the linker of this toolchain
+	depends on !BR2_TOOLCHAIN_EXTERNAL_CODESOURCERY_NIOSII201305
 	help
 	  FLANN is a library for performing fast approximate nearest
 	  neighbor searches in high dimensional spaces. It contains a