tcl: needs threads

Fixes http://autobuild.buildroot.net/results/486/48696710a270ac69d6d62654779f164075cb3451/

Tcl itself has a --disable-threads configure flag, but it unconditially
configures its packages with --enable-threads, causing build failure.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/tcl/Config.in

@@ -3,14 +3,15 @@ config BR2_PACKAGE_TCL
 	# fork()
 	depends on BR2_USE_MMU
 	depends on BR2_INET_IPV6
+	depends on BR2_TOOLCHAIN_HAS_THREADS
 	help
 	  TCL (Tool Command Language) is a simple textual language.
 
 	  http://www.tcl.tk
 
-comment "tcl needs a toolchain w/ ipv6"
+comment "tcl needs a toolchain w/ ipv6, threads"
 	depends on BR2_USE_MMU
-	depends on !BR2_INET_IPV6
+	depends on !BR2_INET_IPV6 || !BR2_TOOLCHAIN_HAS_THREADS
 
 if BR2_PACKAGE_TCL