package/flannel: Add BR2_TOOLCHAIN_HAS_THREADS

flannel uses the cgo package, so needs a toolchain with thread
support.

Signed-off-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/flannel/Config.in

@@ -1,6 +1,11 @@
+comment "flannel needs a toolchain w/ threads"
+	depends on BR2_PACKAGE_HOST_GO_ARCH_SUPPORTS
+	depends on !BR2_TOOLCHAIN_HAS_THREADS
+
 config BR2_PACKAGE_FLANNEL
 	bool "flannel"
 	depends on BR2_PACKAGE_HOST_GO_ARCH_SUPPORTS
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  Flannel is a virtual network that gives a subnet to each
 	  host for use with container runtimes.