lxc: don't build for ARC

Similar to libseccomp, ARC is completely unsupported.

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

utils/lxc/Makefile

@@ -46,6 +46,7 @@ define Package/lxc/Default
   CATEGORY:=Utilities
   TITLE:=LXC userspace tools
   URL:=https://linuxcontainers.org/
+  DEPENDS:=@!arc
 endef
 
 define Package/lxc
@@ -56,7 +57,7 @@ endef
 define Package/lxc-auto
   $(call Package/lxc/Default)
   TITLE:= (initscript)
-  DEPENDS:=+lxc-start +lxc-stop
+  DEPENDS+=lxc-start +lxc-stop
 endef
 
 define Package/lxc-auto/description
@@ -73,7 +74,7 @@ endef
 define Package/lxc-unprivileged
   $(call Package/lxc/Default)
   TITLE:=Helper script for unprivileged containers support
-  DEPENDS:=+shadow-utils +shadow-newuidmap +shadow-newgidmap
+  DEPENDS+=+shadow-utils +shadow-newuidmap +shadow-newgidmap
 endef
 
 define Package/lxc-unprivileged/description
@@ -98,25 +99,25 @@ endef
 define Package/lxc-common
   $(call Package/lxc/Default)
   TITLE:=LXC common files
-  DEPENDS:= lxc
+  DEPENDS+= lxc
 endef
 
 define Package/lxc-hooks
   $(call Package/lxc/Default)
   TITLE:=LXC virtual machine hooks
-  DEPENDS:= lxc
+  DEPENDS+= lxc
 endef
 
 define Package/lxc-templates
   $(call Package/lxc/Default)
   TITLE:=LXC virtual machine templates
-  DEPENDS:= lxc
+  DEPENDS+= lxc
 endef
 
 define Package/lxc-configs
   $(call Package/lxc/Default)
   TITLE:=LXC virtual machine common config files
-  DEPENDS:= lxc
+  DEPENDS+= lxc
 endef
 
 define Package/liblxc
@@ -124,13 +125,13 @@ define Package/liblxc
   SECTION:=libs
   CATEGORY:=Libraries
   TITLE:=LXC userspace library
-  DEPENDS:= lxc +libcap +libpthread +LXC_SECCOMP:libseccomp +libopenssl
+  DEPENDS+= lxc +libcap +libpthread +LXC_SECCOMP:libseccomp +libopenssl
 endef
 
 define Package/lxc-init
   $(call Package/lxc/Default)
   TITLE:=LXC Lua bindings
-  DEPENDS:= lxc +liblxc
+  DEPENDS+= lxc +liblxc
 endef
 
 CONFIGURE_ARGS += \
@@ -245,7 +246,7 @@ define GenPlugin
   define Package/lxc-$(1)
     $(call Package/lxc/Default)
     TITLE:=Utility lxc-$(1) from the LXC userspace tools
-    DEPENDS:= lxc +lxc-common $(2) $(DEPENDS_$(1))
+    DEPENDS+= lxc +lxc-common $(2) $(DEPENDS_$(1))
   endef
 
   define Package/lxc-$(1)/install