toolchain: disallow internal/ctng toolchains for microblaze

While there's some microblaze support in mainline gcc from 4.6.x,
there still seems to be something missing with the uClibc support, so
disable these for now.

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

toolchain/Config.in

@@ -10,6 +10,7 @@ choice
 
 config BR2_TOOLCHAIN_BUILDROOT
 	bool "Buildroot toolchain"
+	depends on !BR2_microblaze
 	select BR2_TOOLCHAIN_HAS_SHADOW_PASSWORDS
 	select BR2_TOOLCHAIN_HAS_THREADS_DEBUG_IF_NEEDED
 
@@ -22,6 +23,7 @@ config BR2_TOOLCHAIN_EXTERNAL
 
 config BR2_TOOLCHAIN_CTNG
 	bool "Crosstool-NG toolchain"
+	depends on !BR2_microblaze
 	select BR2_TOOLCHAIN_HAS_SHADOW_PASSWORDS
 	select BR2_TOOLCHAIN_HAS_THREADS_DEBUG_IF_NEEDED
 	help