luci-app-lxc: Use uname -m as architecture

As containers are basically virtual machines, it should not depend on the
build target but on the real hardware architecture. For example there is plenty
of ARM families (mvebu, sunxi, ...) but all armv7l arms should be able to run
armv7l containers.

Signed-off-by: Michal Hrusecky <michal.hrusecky@nic.cz>

utils/luci-app-lxc/files/controller/lxc.lua

@@ -78,7 +78,10 @@ function lxc_create(lxc_name, lxc_template)
 		return luci.http.write("1")
 	end
 
-	local target = _G.DISTRIB_TARGET:match('([^/]+)')
+	local f = io.popen('uname -m', 'r')
+	local target = f:read('*a')
+	f:close()
+	target = target:gsub("^%s*(.-)%s*$", "%1")
 
 	local lxc_dist = lxc_template:gsub("(.*):(.*)", '%1')
 	local lxc_release = lxc_template:gsub("(.*):(.*)", '%2')