Update tengo vendor and load the stdlib. Fixes #789 (#792)

vendor/github.com/d5/tengo/runtime/errors.go

@@ -6,3 +6,6 @@ import (
 
 // ErrStackOverflow is a stack overflow error.
 var ErrStackOverflow = errors.New("stack overflow")
+
+// ErrObjectAllocLimit is an objects allocation limit error.
+var ErrObjectAllocLimit = errors.New("object allocation limit exceeded")

vendor/github.com/d5/tengo/runtime/frame.go

@@ -7,7 +7,7 @@ import (
 // Frame represents a function call frame.
 type Frame struct {
 	fn          *objects.CompiledFunction
-	freeVars    []*objects.Object
+	freeVars    []*objects.ObjectPtr
 	ip          int
 	basePointer int
 }