move enable_localaccount.sh, make pam_offline use it

src/platform/pam_offline/username_password.cc

Index: src/platform/pam_offline/username_password.cc
diff --git a/src/platform/pam_offline/username_password.cc b/src/platform/pam_offline/username_password.cc
index bf13d9e1d8be29cfd6fa10cf82f0a1d7d49ff22d..40b7ec741f955f17487ca7def4442000fe27da65 100644
--- a/src/platform/pam_offline/username_password.cc
+++ b/src/platform/pam_offline/username_password.cc
@@ -52,6 +52,12 @@ void UsernamePassword::Init(const char *username,
   username_[username_length] = password_[password_length] = 0;
 }
 
+#ifdef CHROMEOS_PAM_LOCALACCOUNT
+bool UsernamePassword::IsLocalAccount() const {
+  return 0 == strncmp(username_, kLocalAccount, strlen(kLocalAccount));
+}
+#endif
+
 void UsernamePassword::GetFullUsername(char *name_buffer, int length) const {
   strncpy(name_buffer, username_, length);
 }