nut: now needs C++ support

Fixes http://autobuild.buildroot.net/results/8c5/8c5dc5f09e2dcb2a3aba1c451a53de8e79d531dc/

After the version bump, nut now unconditionally builds a C++ client library,
so adjust the dependencies to match.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/nut/Config.in

@@ -1,6 +1,11 @@
+comment "nut needs a toolchain w/ C++"
+	depends on BR2_USE_MMU
+	depends on !BR2_INSTALL_LIBSTDCPP
+
 config BR2_PACKAGE_NUT
 	bool "nut"
 	depends on BR2_USE_MMU # fork()
+	depends on BR2_INSTALL_LIBSTDCPP
 	help
 	  Network UPS tools