hugolib: Fix layout lookup order for Render func

Will have to fix this in a better way later in relation to the non-renderable pages.

But this commit brings the Hugo Benchmark down to "only slightly slower" than master.

```
benchmark           old ns/op       new ns/op       delta
BenchmarkHugo-4     10074504521     10071236251     -0.03%

benchmark           old allocs     new allocs     delta
BenchmarkHugo-4     43623091       49271859       +12.95%

benchmark           old bytes      new bytes      delta
BenchmarkHugo-4     9468322704     9725848376     +2.72%
```

Which is something we can work with.

1 files changed, 4 insertions, 5 deletions

diff --git a/hugolib/page.go b/hugolib/page.go
index 1308aa49d..2f21eb313 100644
--- a/hugolib/page.go
+++ b/hugolib/page.go
@@ -657,8 +657,8 @@ func (p *Page) Section() string {
 }
 
 func (p *Page) layouts(layouts ...string) []string {
-	// TODO(bep) output
-	if len(p.layoutsCalculated) > 0 {
+	// TODO(bep) output the logic here needs to be redone.
+	if len(layouts) == 0 && len(p.layoutsCalculated) > 0 {
 		return p.layoutsCalculated
 	}
 
@@ -1285,9 +1285,8 @@ func (p *Page) Menus() PageMenus {
 	return p.pageMenus
 }
 
-func (p *Page) Render(layouts ...string) template.HTML {
-	l := p.layouts(layouts...)
-
+func (p *Page) Render(layout ...string) template.HTML {
+	l := p.layouts(layout...)
 	return p.s.Tmpl.ExecuteTemplateToHTML(p, l...)
 }