cmd/compile: move Node.Param, Node.Funcdepth into Node.Name; remove Node.Walkgen

$ sizeof -p cmd/compile/internal/gc Node
Node 176
$

Change-Id: Ibf1ab531a60d4af8a0c242c0e504f4fd50cd5b36
Reviewed-on: https://go-review.googlesource.com/10530
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
diff --git a/src/cmd/compile/internal/gc/export.go b/src/cmd/compile/internal/gc/export.go
index 33aa0ad..0d64fdb 100644
--- a/src/cmd/compile/internal/gc/export.go
+++ b/src/cmd/compile/internal/gc/export.go
@@ -64,7 +64,7 @@
 	if (ctxt != PEXTERN && ctxt != PFUNC) || dclcontext != PEXTERN {
 		return
 	}
-	if n.Param != nil && n.Param.Ntype != nil && n.Param.Ntype.Op == OTFUNC && n.Param.Ntype.Left != nil { // method
+	if n.Name.Param != nil && n.Name.Param.Ntype != nil && n.Name.Param.Ntype.Op == OTFUNC && n.Name.Param.Ntype.Left != nil { // method
 		return
 	}