Bugfix/code clean using gcc warnings (#371)

* Enable extra GCC warnings to discover subtle bugs

* convert c++ comments to c comments

* cleanup pedantic compiler warnings

* Compile apps with GNU89 GNU99 GNU11 and GNU17

Co-authored-by: Steve Karg <skarg@users.sourceforge.net>

test/bacnet/basic/object/device/CMakeLists.txt

@@ -74,6 +74,7 @@ add_executable(${PROJECT_NAME}
 	${SRC_DIR}/bacnet/basic/service/h_cov.c
 	${SRC_DIR}/bacnet/basic/service/h_wp.c
 	${SRC_DIR}/bacnet/basic/sys/bigend.c
+	${SRC_DIR}/bacnet/basic/sys/debug.c
 	${SRC_DIR}/bacnet/basic/sys/keylist.c
 	${SRC_DIR}/bacnet/basic/tsm/tsm.c
 	${SRC_DIR}/bacnet/datalink/bvlc.c