storage: fix local_call not finding persistent func

Currently, if function was created as C stored procedure or as Lua
persistent function (with body argument) via box.schema.func.create,
all types of router.call and router.map_callrw cannot find it and
return `Procedure 'name' is not defined` error.

This is cased by the fact that both of these function use local_call,
which invokes net_box.self.call, which doesn't currently work with
C stored procedures due to the bug. Let's use box.func, where it's
possible instead of net_box.self.call in local_call.

Closes #436

NO_DOC=bugfix

test/storage-luatest/storage_1_test.lua

@@ -168,3 +168,17 @@ test_group.test_recovery_bucket_stat = function(g)
 
     vtest.cluster_cfg(g, global_cfg)
 end
+
+test_group.test_local_call = function(g)
+    -- box.func was introduced in 2.2.0.
+    t.run_only_if(vutil.version_is_at_least(2, 2, 0, nil, 0, 0))
+    g.replica_1_a:exec(function()
+        local body = [[function(a, b) return a + b end]]
+        box.schema.func.create('sum', {body = body})
+        local bid = _G.get_first_bucket()
+        local ok, ret = ivshard.storage.call(bid, 'read', 'sum', {1, 2})
+        ilt.assert_equals(ret, 3)
+        ilt.assert_equals(ok, true)
+        box.func.sum:drop()
+    end)
+end

vshard/storage/init.lua

@@ -266,7 +266,17 @@ end
 -- exceptions are not allowed.
 --
 local function local_call(func_name, args)
-    return pcall(netbox_self_call, netbox_self, func_name, args)
+    -- If function was created with box.schema.func we call it via
+    -- func.call API, as net_box.self.call doesn't work with C stored
+    -- procedures up to Tarantool 3.X. If box.func is inaccessible,
+    -- which is true for all versions below 2.2, we fallback to
+    -- net_box.self.call too.
+    if box.func == nil or box.func[func_name] == nil then
+        return pcall(netbox_self_call, netbox_self, func_name, args)
+    end
+
+    local func = box.func[func_name]
+    return pcall(func.call, func, args)
 end
 
 local function master_call(replicaset, func, args, opts)