Move graph guard condition destruction to rmw_context_fini. (#150)

That's because during rmw_shutdown(), the graph guard
condition may still be in use in rwm_wait() and friends.
Fix this by moving the destruction of it later, into
rmw_context_fini.

Signed-off-by: Chris Lalancette <[email protected]>

rmw_zenoh_cpp/src/rmw_init.cpp

@@ -377,15 +377,6 @@ rmw_shutdown(rmw_context_t * context)
     return RMW_RET_ERROR;
   }
 
-  const rcutils_allocator_t * allocator = &context->options.allocator;
-
-  RMW_TRY_DESTRUCTOR(
-    static_cast<GuardCondition *>(context->impl->graph_guard_condition->data)->~GuardCondition(),
-    GuardCondition, );
-  allocator->deallocate(context->impl->graph_guard_condition->data, allocator->state);
-
-  allocator->deallocate(context->impl->graph_guard_condition, allocator->state);
-
   context->impl->is_shutdown = true;
 
   return RMW_RET_OK;
@@ -411,10 +402,18 @@ rmw_context_fini(rmw_context_t * context)
     return RMW_RET_INVALID_ARGUMENT;
   }
 
-  RMW_TRY_DESTRUCTOR(context->impl->~rmw_context_impl_t(), rmw_context_impl_t, );
-
   const rcutils_allocator_t * allocator = &context->options.allocator;
 
+  RMW_TRY_DESTRUCTOR(
+    static_cast<GuardCondition *>(context->impl->graph_guard_condition->data)->~GuardCondition(),
+    GuardCondition, );
+  allocator->deallocate(context->impl->graph_guard_condition->data, allocator->state);
+
+  allocator->deallocate(context->impl->graph_guard_condition, allocator->state);
+  context->impl->graph_guard_condition = nullptr;
+
+  RMW_TRY_DESTRUCTOR(context->impl->~rmw_context_impl_t(), rmw_context_impl_t, );
+
   allocator->deallocate(context->impl, allocator->state);
 
   rmw_ret_t ret = rmw_init_options_fini(&context->options);