gst-plugins-bad: decklink plugin needs C++ support

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/multimedia/gst-plugins-bad/Config.in

@@ -55,8 +55,12 @@ config BR2_PACKAGE_GST_PLUGINS_BAD_PLUGIN_DEBUGUTILS
 	bool "debugutils"
 
 config BR2_PACKAGE_GST_PLUGINS_BAD_PLUGIN_DECKLINK
+	depends on BR2_INSTALL_LIBSTDCPP
 	bool "decklink"
 
+comment "decklink requires a toolchain with C++ support enabled"
+	depends on !BR2_INSTALL_LIBSTDCPP
+
 config BR2_PACKAGE_GST_PLUGINS_BAD_PLUGIN_DTMF
 	bool "dtmf"