cmd/compile/internal/gc: use slice instead of linked list for nodes to export

Change-Id: Ib79ab787fdc90a5a29b25474d91afa9bfaf51276
Reviewed-on: https://go-review.googlesource.com/13589
Reviewed-by: Minux Ma <minux@golang.org>
diff --git a/src/cmd/compile/internal/gc/go.go b/src/cmd/compile/internal/gc/go.go
index 9874ff7..be56b81 100644
--- a/src/cmd/compile/internal/gc/go.go
+++ b/src/cmd/compile/internal/gc/go.go
@@ -586,7 +586,7 @@
 
 var externdcl *NodeList
 
-var exportlist *NodeList
+var exportlist []*Node
 
 var importlist *NodeList // imported functions and methods with inlinable bodies