fix build constraint go1.8 (#993)

jro7 · vishr · commit 6c54ff78a235 · 2017-08-22T08:26:26.000-07:00
* fix build constraint go1.8

go1.8 wasn't properly excluded

* Update util_go17.go
diff --git a/util_go17.go b/util_go17.go
@@ -1,4 +1,4 @@
-// +build go1.7,!go1.8
+// +build go1.7, !go1.8
 
 package echo
 
