[host]linux/mips: copy mips64 definition from mips.

It just copy from mips, so it may be corrupt, but I can not check it.
If something wrong, please open an issue.

host/host_linux_mips64.go

@@ -0,0 +1,43 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs types_linux.go
+
+package host
+
+const (
+	sizeofPtr      = 0x4
+	sizeofShort    = 0x2
+	sizeofInt      = 0x4
+	sizeofLong     = 0x4
+	sizeofLongLong = 0x8
+	sizeOfUtmp     = 0x180
+)
+
+type (
+	_C_short     int16
+	_C_int       int32
+	_C_long      int32
+	_C_long_long int64
+)
+
+type utmp struct {
+	Type      int16
+	Pad_cgo_0 [2]byte
+	Pid       int32
+	Line      [32]int8
+	Id        [4]int8
+	User      [32]int8
+	Host      [256]int8
+	Exit      exit_status
+	Session   int32
+	Tv        timeval
+	Addr_v6   [4]int32
+	X__unused [20]int8
+}
+type exit_status struct {
+	Termination int16
+	Exit        int16
+}
+type timeval struct {
+	Sec  int32
+	Usec int32
+}