toolchain: mark mklibs as broken

mklibs is a broken option, so mark it as so pending a proper fixup or
punting it.

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

toolchain/mklibs/Config.in

@@ -1,5 +1,6 @@
 config BR2_MKLIBS
 	bool "Run mklibs on the built root filesystem"
+	depends on BROKEN
 	help
 	  Recompiles all the shared libraries to only include the
 	  symbols actually needed to run the binaries on the target