pkg/astutil,pkg/elfwriter: fix package doc (#3753)

pkg/astutil/astutil.go

@@ -1,6 +1,5 @@
 // This package contains utility functions used by pkg/proc to generate
 // ast.Expr expressions.
-
 package astutil
 
 import (

pkg/elfwriter/writer.go

@@ -3,7 +3,6 @@
 // This package is incomplete, only features needed to write core files are
 // implemented, notably missing:
 // - program headers at the beginning of the file
-
 package elfwriter
 
 import (