rt-tests: fix typo in Config.in threads negative logic

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/rt-tests/Config.in

@@ -17,4 +17,4 @@ config BR2_PACKAGE_RT_TESTS
 	  http://rt.wiki.kernel.org
 
 comment "rt-tests requires a toolchain with threads support"
-	!BR2_TOOLCHAIN_HAS_THREADS
+	depends on !BR2_TOOLCHAIN_HAS_THREADS