control: JSON parsing compile framework

Add the enabling framework of use of JSON config files for fan control.

Tested:
    Compile passes when `--enable-json` configure flag given
    Compile passes without enabling JSON
    No functional change when not using JSON

Change-Id: Ic70bfc63ad74cb79559ed839784cd214df403cb2
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/manager.hpp b/control/manager.hpp
index 34ae0b9..a2e44f5 100644
--- a/control/manager.hpp
+++ b/control/manager.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "config.h"
+
 #include "types.hpp"
 #include "zone.hpp"
 
@@ -65,7 +67,7 @@
      * The fan zones in the system
      */
     ZoneMap _zones;
-
+#ifndef CONTROL_USE_JSON
     /**
      * The fan zone layout for the system.
      * This is generated data.
@@ -78,6 +80,7 @@
      * to give them a chance to get there.
      */
     static const unsigned int _powerOnDelay;
+#endif
 };
 
 } // namespace control