runtime: move arch_mips64(le)?.go into runtime/internal/sys

Somehow these were left out of the orignial CL.

Updates #11647

Change-Id: I058a30eaa25fbb72d60e7fb6bc9ff0a3b54fdb2a
Reviewed-on: https://go-review.googlesource.com/16870Reviewed-by: Minux Ma <minux@golang.org>

src/runtime/arch_mips64.go → src/runtime/internal/sys/arch_mips64.go

@@ -2,18 +2,18 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package runtime
+package sys
 
 const (
-	thechar        = '0'
-	_BigEndian     = 1
-	_CacheLineSize = 32
-	_PhysPageSize  = 16384
-	_PCQuantum     = 4
-	_Int64Align    = 8
-	hugePageSize   = 0
-	minFrameSize   = 8
+	TheChar       = '0'
+	BigEndian     = 1
+	CacheLineSize = 32
+	PhysPageSize  = 16384
+	PCQuantum     = 4
+	Int64Align    = 8
+	HugePageSize  = 0
+	MinFrameSize  = 8
 )
 
-type uintreg uint64
-type intptr int64 // TODO(rsc): remove
+type Uintreg uint64
+type Intptr int64 // TODO(rsc): remove

src/runtime/arch_mips64le.go → src/runtime/internal/sys/arch_mips64le.go

@@ -2,18 +2,18 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package runtime
+package sys
 
 const (
-	thechar        = '0'
-	_BigEndian     = 0
-	_CacheLineSize = 32
-	_PhysPageSize  = 16384
-	_PCQuantum     = 4
-	_Int64Align    = 8
-	hugePageSize   = 0
-	minFrameSize   = 8
+	TheChar       = '0'
+	BigEndian     = 0
+	CacheLineSize = 32
+	PhysPageSize  = 16384
+	PCQuantum     = 4
+	Int64Align    = 8
+	HugePageSize  = 0
+	MinFrameSize  = 8
 )
 
-type uintreg uint64
-type intptr int64 // TODO(rsc): remove
+type Uintreg uint64
+type Intptr int64 // TODO(rsc): remove