Use upstream whatsapp again (#809)

vendor/golang.org/x/sys/cpu/cpu_linux.go

@@ -0,0 +1,55 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//+build !amd64,!amd64p32,!386
+
+package cpu
+
+import (
+	"io/ioutil"
+)
+
+const (
+	_AT_HWCAP  = 16
+	_AT_HWCAP2 = 26
+
+	procAuxv = "/proc/self/auxv"
+
+	uintSize = int(32 << (^uint(0) >> 63))
+)
+
+// For those platforms don't have a 'cpuid' equivalent we use HWCAP/HWCAP2
+// These are initialized in cpu_$GOARCH.go
+// and should not be changed after they are initialized.
+var hwCap uint
+var hwCap2 uint
+
+func init() {
+	buf, err := ioutil.ReadFile(procAuxv)
+	if err != nil {
+		panic("read proc auxv failed: " + err.Error())
+	}
+
+	bo := hostByteOrder()
+	for len(buf) >= 2*(uintSize/8) {
+		var tag, val uint
+		switch uintSize {
+		case 32:
+			tag = uint(bo.Uint32(buf[0:]))
+			val = uint(bo.Uint32(buf[4:]))
+			buf = buf[8:]
+		case 64:
+			tag = uint(bo.Uint64(buf[0:]))
+			val = uint(bo.Uint64(buf[8:]))
+			buf = buf[16:]
+		}
+		switch tag {
+		case _AT_HWCAP:
+			hwCap = val
+		case _AT_HWCAP2:
+			hwCap2 = val
+		}
+	}
+	doinit()
+}