Fix Kafka compilation (#162)

Author: awegrzyn

CMakeLists.txt

@@ -139,7 +139,7 @@ target_compile_definitions(Monitoring
     $<$<BOOL:${APPLE}>:O2_MONITORING_OS_MAC>
     $<$<BOOL:${LINUX}>:O2_MONITORING_OS_LINUX>
     $<$<BOOL:${ApMon_FOUND}>:O2_MONITORING_WITH_APPMON>
-    $<$<BOOL:${RdKafka_FOUND}>:O2_MONITORING_WITH__WITH_KAFKA>
+    $<$<BOOL:${RdKafka_FOUND}>:O2_MONITORING_WITH_KAFKA>
   )
 
 # Use C++17

src/MonitoringFactory.cxx

@@ -30,7 +30,7 @@
 #include "Backends/ApMonBackend.h"
 #endif
 
-#ifdef O2_MONITORING__WITH_KAFKA
+#ifdef O2_MONITORING_WITH_KAFKA
 #include "Backends/Kafka.h"
 #endif
 
@@ -39,7 +39,7 @@ namespace o2
 /// ALICE O2 Monitoring system
 namespace monitoring
 {
-#ifdef _WITH_KAFKA
+#ifdef O2_MONITORING_WITH_KAFKA
 std::unique_ptr<Backend> getKafka(http::url uri)
 {
   if (uri.search.size() > 0) {