CI tests are failing due to gofmt formatting

[kamphaus]

CI output:

Go code is not properly formatted. Use 'gofmt'.
diff -u ast/ast_test.go.orig ast/ast_test.go
--- ast/ast_test.go.orig    2018-06-18 21:14:51.686055652 +0000
+++ ast/ast_test.go 2018-06-18 21:14:51.686055652 +0000
@@ -58,7 +58,7 @@
 }

 var lines = []string{
-   // c2go ast sqlite3.c | head -5000 | sed 's/^[ |`-]*//' | sed 's/<<<NULL>>>/NullStmt/g' | gawk 'length > 0 {print "`" $0 "`,"}'
+// c2go ast sqlite3.c | head -5000 | sed 's/^[ |`-]*//' | sed 's/<<<NULL>>>/NullStmt/g' | gawk 'length > 0 {print "`" $0 "`,"}'
 }

This is due to the changes from https://github.com/elliotchance/c2go/pull/751