bmcweb: remove warning about coroutines

Boost coroutines seems to be in use in sdbusplus asio, despite its
depcrecation in boost.  Silence the warning.

Change-Id: Ic72545604f597a7ce937710068b040362ab0d224
Signed-off-by: Ed Tanous <ed.tanous@intel.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 184a501..80c132b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -114,6 +114,7 @@
 add_definitions (-DBOOST_ALL_NO_LIB)
 add_definitions (-DBOOST_NO_RTTI)
 add_definitions (-DBOOST_NO_TYPEID)
+add_definitions (-DBOOST_COROUTINES_NO_DEPRECATION_WARNING)
 
 find_package (Boost 1.66 REQUIRED)
 include_directories (${BOOST_SRC_DIR})