net, text/tabwriter: use cap arg to make

Changes generated by:

gofmt -w -r 'make(a, b)[0:0] -> make(a, 0, b)' src/pkg

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/24820045

src/pkg/net/dnsconfig_unix.go

@@ -27,7 +27,7 @@ func dnsReadConfig() (*dnsConfig, error) {
 		return nil, &DNSConfigError{err}
 	}
 	conf := new(dnsConfig)
-	conf.servers = make([]string, 3)[0:0] // small, but the standard limit
+	conf.servers = make([]string, 0, 3) // small, but the standard limit
 	conf.search = make([]string, 0)
 	conf.ndots = 1
 	conf.timeout = 5

src/pkg/net/parse.go

@@ -67,7 +67,7 @@ func open(name string) (*file, error) {
 	if err != nil {
 		return nil, err
 	}
-	return &file{fd, make([]byte, os.Getpagesize())[0:0], false}, nil
+	return &file{fd, make([]byte, 0, os.Getpagesize()), false}, nil
 }
 
 func byteIndex(s string, c byte) int {

src/pkg/text/tabwriter/tabwriter_test.go

@@ -14,7 +14,7 @@ type buffer struct {
 	a []byte
 }
 
-func (b *buffer) init(n int) { b.a = make([]byte, n)[0:0] }
+func (b *buffer) init(n int) { b.a = make([]byte, 0, n) }
 
 func (b *buffer) clear() { b.a = b.a[0:0] }