ruby: needs thread support

Fixes:

   http://autobuild.buildroot.org/results/7c6/7c6cc07e360aa998957a48e834b8cc086282d716/build-end.log

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

package/ruby/Config.in

@@ -1,10 +1,11 @@
 config BR2_PACKAGE_RUBY
 	bool "ruby"
 	depends on BR2_USE_WCHAR
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  Object Oriented Scripting Language.
 
 	  http://www.ruby-lang.org/
 
-comment "ruby needs a toolchain w/ wchar"
-	depends on !BR2_USE_WCHAR
+comment "ruby needs a toolchain w/ wchar, threads"
+	depends on !BR2_USE_WCHAR || !BR2_TOOLCHAIN_HAS_THREADS