Simplify Utsname string conversion

Use Utsname from golang.org/x/sys/unix which contains byte array
instead of int8/uint8 array members. This allows to simplify the string
conversions of these members and the marshal.FromUtsname functions are
no longer needed.

common/marshal/marshal_darwin.go

@@ -1,4 +0,0 @@
-package marshal
-
-// Stub to make the compiler happy in darwin (i.e. avoid "no buildable Go source
-// files in" error)

common/marshal/marshal_linux.go

@@ -1,17 +0,0 @@
-// +build !arm
-
-package marshal
-
-// FromUtsname reads the C-strings from syscall.Utsname and transforms them to Go
-// strings
-func FromUtsname(ca [65]int8) string {
-	s := make([]byte, len(ca))
-	var lens int
-	for ; lens < len(ca); lens++ {
-		if ca[lens] == 0 {
-			break
-		}
-		s[lens] = uint8(ca[lens])
-	}
-	return string(s[0:lens])
-}

common/marshal/marshal_linux_arm.go

@@ -1,15 +0,0 @@
-package marshal
-
-// FromUtsname reads the C-strings from syscall.Utsname and transforms them to Go
-// strings
-func FromUtsname(ca [65]uint8) string {
-	s := make([]byte, len(ca))
-	var lens int
-	for ; lens < len(ca); lens++ {
-		if ca[lens] == 0 {
-			break
-		}
-		s[lens] = uint8(ca[lens])
-	}
-	return string(s[0:lens])
-}