fix -Wdeprecated-increment-bool warnings

include/ACGL/Utils/PerformanceTimer.hh

@@ -140,7 +140,10 @@ class CSystemTimer : public CProcessTimer
 public:
     CSystemTimer() : CProcessTimer() {
 		static bool warned = false;
-		if ( !warned++ ) ACGL::Utils::error() << "No system timer present on this OS - fallback to process time" << std::endl;
+        if ( !warned ) {
+            ACGL::Utils::error() << "No system timer present on this OS - fallback to process time" << std::endl;
+            warned = true;
+        }
     }
 };
 
@@ -150,7 +153,10 @@ class CThreadTimer : public CProcessTimer
 public:
 	CThreadTimer() : CProcessTimer() {
 		static bool warned = false;
-		if ( !warned++ ) ACGL::Utils::error() << "No thread timer present on this OS - fallback to process time" << std::endl;
+        if ( !warned ) {
+            ACGL::Utils::error() << "No thread timer present on this OS - fallback to process time" << std::endl;
+            warned = true;
+        }
     }
 };