Force usage of x64 registry on x64 systems from x86 builds

Building an app for a x86 environment and running that app on an amd64 environment led to a `file not found` (aka failed to lookup relevant registry key) error. The added flag gets ignored on x86 systems, but will be followed on x64 systems.

fixes denisbrodbeck#2

Author: denisbrodbeck

id_windows.go

@@ -9,7 +9,7 @@ import (
 // machineID returns the key MachineGuid in registry `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography`.
 // If there is an error running the commad an empty string is returned.
 func machineID() (string, error) {
-	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Cryptography`, registry.QUERY_VALUE)
+	k, err := registry.OpenKey(registry.LOCAL_MACHINE, `SOFTWARE\Microsoft\Cryptography`, registry.QUERY_VALUE|registry.WOW64_64KEY)
 	if err != nil {
 		return "", err
 	}