package/bird: BFD protocol needs threads

Fixes:
 - http://autobuild.buildroot.org/results/e1f879cb34f9cfbbd14b75f63d25897c5bee53cd

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/bird/Config.in

@@ -29,9 +29,13 @@ config BR2_PACKAGE_BIRD_BABEL
 
 config BR2_PACKAGE_BIRD_BFD
 	bool "bfd"
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  Enable BFD protocol.
 
+comment "BFD protocol needs a toolchain w/ threads"
+	depends on !BR2_TOOLCHAIN_HAS_THREADS
+
 config BR2_PACKAGE_BIRD_BGP
 	bool "bgp"
 	default y