liburcu: Don't build under ARC, not even InstallDev

This should finally get rid of buildbot failures.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

libs/liburcu/Makefile

@@ -32,19 +32,21 @@ define Package/liburcu
 	CATEGORY:=Libraries
 	TITLE:=User-space Read-Copy-Update library
 	URL:=https://lttng.org/
-	DEPENDS:=+libpthread @!TARGET_arc770 @!TARGET_archs38
+	DEPENDS:=+libpthread @!arc
 endef
 
 define Package/liburcu/description
 	Userspace Read-Copy-Update library.
 endef
 
+ifeq ($(CONFIG_arc),)
 define Build/InstallDev
 	$(INSTALL_DIR)						$(1)/usr/include
 	$(CP) $(PKG_INSTALL_DIR)/usr/include/urcu*		$(1)/usr/include/
 	$(INSTALL_DIR)						$(1)/usr/lib
 	$(CP) $(PKG_INSTALL_DIR)/usr/lib/liburcu*.{a,so*}	$(1)/usr/lib/
 endef
+endif
 
 define Package/liburcu/install
 	$(INSTALL_DIR)					$(1)/usr/lib