liburcu: only some architectures are supported

Make sure that liburcu (and the packages that select it) cannot be
enabled on the architectures that are not supported. At the moment,
only x86, x86-64, PowerPC and ARM are supported.

[Peter: add armeb as well]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/liburcu/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_LIBURCU
 	bool "liburcu"
+	depends on BR2_arm || BR2_armeb || BR2_i386 || BR2_powerpc || BR2_x86_64
 	help
 	  Userspace implementation of the Read-Copy-Update (RCU)
 	  synchronization mechanism. This library is mainly used by

package/lttng-libust/Config.in

@@ -6,6 +6,8 @@ config BR2_PACKAGE_LTTNG_LIBUST
 	# util-linux needs wchar and largefile
 	depends on BR2_USE_WCHAR
 	depends on BR2_LARGEFILE
+	# liburcu only works on some architectures
+	depends on BR2_arm || BR2_armeb || BR2_i386 || BR2_powerpc || BR2_x86_64
 	help
 	  Userspace tracing library for the Lttng tracing
 	  infrastructure. It allows userspace programs to create

package/lttng-tools/Config.in

@@ -3,6 +3,8 @@ config BR2_PACKAGE_LTTNG_TOOLS
 	depends on BR2_PACKAGE_LTTNG_MODULES
 	select BR2_PACKAGE_LIBURCU
 	select BR2_PACKAGE_POPT
+	# liburcu only works on some architectures
+	depends on BR2_arm || BR2_armeb || BR2_i386 || BR2_powerpc || BR2_x86_64
 	help
 	  Userspace utilities for the LTTng 2.0 tracing
 	  infrastructure.