unix: remove unnecessary use of unsafe.Pointer.

Change-Id: I7ae67ce410ae2816c2f3e8ecb26e46265aa11d7f
Reviewed-on: https://go-review.googlesource.com/73771
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

unix/syscall_linux.go

@@ -926,7 +926,7 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 	msg.Namelen = uint32(SizeofSockaddrAny)
 	var iov Iovec
 	if len(p) > 0 {
-		iov.Base = (*byte)(unsafe.Pointer(&p[0]))
+		iov.Base = &p[0]
 		iov.SetLen(len(p))
 	}
 	var dummy byte
@@ -941,7 +941,7 @@ func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from
 			iov.Base = &dummy
 			iov.SetLen(1)
 		}
-		msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
+		msg.Control = &oob[0]
 		msg.SetControllen(len(oob))
 	}
 	msg.Iov = &iov
@@ -974,11 +974,11 @@ func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error)
 		}
 	}
 	var msg Msghdr
-	msg.Name = (*byte)(unsafe.Pointer(ptr))
+	msg.Name = (*byte)(ptr)
 	msg.Namelen = uint32(salen)
 	var iov Iovec
 	if len(p) > 0 {
-		iov.Base = (*byte)(unsafe.Pointer(&p[0]))
+		iov.Base = &p[0]
 		iov.SetLen(len(p))
 	}
 	var dummy byte
@@ -993,7 +993,7 @@ func SendmsgN(fd int, p, oob []byte, to Sockaddr, flags int) (n int, err error)
 			iov.Base = &dummy
 			iov.SetLen(1)
 		}
-		msg.Control = (*byte)(unsafe.Pointer(&oob[0]))
+		msg.Control = &oob[0]
 		msg.SetControllen(len(oob))
 	}
 	msg.Iov = &iov