cmd: remove bio.BufReader and bio.BufWriter

bio.BufReader was never used.

bio.BufWriter was used to wrap an existing io.Writer, but the
bio.Writer returned would not be seekable, so replace all occurences
with bufio.Reader instead.

Change-Id: I9c6779e35c63178aa4e104c17bb5bb8b52de0359
Reviewed-on: https://go-review.googlesource.com/21722
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/compile/internal/gc/bexport.go b/src/cmd/compile/internal/gc/bexport.go
index bb0a34e..15e5e3a 100644
--- a/src/cmd/compile/internal/gc/bexport.go
+++ b/src/cmd/compile/internal/gc/bexport.go
@@ -90,9 +90,9 @@
 package gc
 
 import (
+	"bufio"
 	"bytes"
 	"cmd/compile/internal/big"
-	"cmd/internal/bio"
 	"encoding/binary"
 	"fmt"
 	"sort"
@@ -124,7 +124,7 @@
 const exportInlined = true // default: true
 
 type exporter struct {
-	out      *bio.Writer
+	out      *bufio.Writer
 	pkgIndex map[*Pkg]int
 	typIndex map[*Type]int
 	inlined  []*Func
@@ -136,7 +136,7 @@
 }
 
 // export writes the exportlist for localpkg to out and returns the number of bytes written.
-func export(out *bio.Writer, trace bool) int {
+func export(out *bufio.Writer, trace bool) int {
 	p := exporter{
 		out:      out,
 		pkgIndex: make(map[*Pkg]int),
diff --git a/src/cmd/compile/internal/gc/export.go b/src/cmd/compile/internal/gc/export.go
index 2f94b9c..dc7c086 100644
--- a/src/cmd/compile/internal/gc/export.go
+++ b/src/cmd/compile/internal/gc/export.go
@@ -384,7 +384,7 @@
 		if debugFormat {
 			// save a copy of the export data
 			var copy bytes.Buffer
-			bcopy := bio.BufWriter(&copy)
+			bcopy := bufio.NewWriter(&copy)
 			size = export(bcopy, Debug_export != 0)
 			bcopy.Flush() // flushing to bytes.Buffer cannot fail
 			if n, err := bout.Write(copy.Bytes()); n != size || err != nil {
@@ -407,7 +407,7 @@
 			pkgs = savedPkgs
 			pkgMap = savedPkgMap
 		} else {
-			size = export(bout, Debug_export != 0)
+			size = export(bout.Writer(), Debug_export != 0)
 		}
 		exportf("\n$$\n")
 	} else {
diff --git a/src/cmd/compile/internal/gc/go.go b/src/cmd/compile/internal/gc/go.go
index ec7e219..d9b28ff 100644
--- a/src/cmd/compile/internal/gc/go.go
+++ b/src/cmd/compile/internal/gc/go.go
@@ -5,6 +5,7 @@
 package gc
 
 import (
+	"bufio"
 	"cmd/compile/internal/ssa"
 	"cmd/internal/bio"
 	"cmd/internal/obj"
@@ -288,7 +289,7 @@
 
 var writearchive int
 
-var bstdout *bio.Writer
+var bstdout *bufio.Writer
 
 var Nacl bool
 
diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index 03143f5..26acf88 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -9,7 +9,6 @@
 import (
 	"bufio"
 	"cmd/compile/internal/ssa"
-	"cmd/internal/bio"
 	"cmd/internal/obj"
 	"cmd/internal/sys"
 	"flag"
@@ -104,7 +103,7 @@
 
 	Ctxt = obj.Linknew(Thearch.LinkArch)
 	Ctxt.DiagFunc = Yyerror
-	bstdout = bio.BufWriter(os.Stdout)
+	bstdout = bufio.NewWriter(os.Stdout)
 	Ctxt.Bso = bstdout
 
 	localpkg = mkpkg("")