Use public for enable_shared_from_this

The default inheritance for class is private,
the weak_from_this will always returns NULL.
This causes the SOL data is out of sync, change it to public.

Tested:
Ipmitool sol works the same as SOL in webui

Signed-off-by: Yong Li <yong.b.li@linux.intel.com>
Change-Id: I8f80521e58684c178973447e40c7a10dd2ae18c9
diff --git a/sol/sol_context.hpp b/sol/sol_context.hpp
index 50be65f..a857c7f 100644
--- a/sol/sol_context.hpp
+++ b/sol/sol_context.hpp
@@ -149,7 +149,7 @@
  *  interfaces to handle incoming SOL payload, send response and send outbound
  *  SOL payload.
  */
-class Context : std::enable_shared_from_this<Context>
+class Context : public std::enable_shared_from_this<Context>
 {
   public:
     Context() = delete;