toolchain-external: sync toolchain options with the internal toolchain

The internal toolchain defaults to thread support enabled (and
most external toolchains have thread support as well), so enable
BR2_TOOLCHAIN_EXTERNAL_HAS_THREADS by default.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

toolchain/toolchain-external/Config.in

@@ -311,6 +311,7 @@ config BR2_TOOLCHAIN_EXTERNAL_PROGRAM_INVOCATION
 config BR2_TOOLCHAIN_EXTERNAL_HAS_THREADS
 	bool "Toolchain has threads support?"
 	select BR2_TOOLCHAIN_HAS_THREADS
+	default y
 	help
 	  Select this option if your external toolchain has thread
 	  support. If you don't know, leave the default value,