Don't force optimization flags on non-release configurations

Author: AMDmi3

src/CMakeLists.txt

@@ -14,8 +14,8 @@ set (Tutorial_VERSION_MAJOR 1)
 set (Tutorial_VERSION_MINOR 1)
 
 # It's pretty safe and provide big speedup for our packet processor and patricia code
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2 ")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O2")
+set(CMAKE_C_FLAGS_RELEASE "-O2")
+set(CMAKE_CXX_FLAGS_RELEASE "-O2")
 
 set(FASTNETMON_PROFILER OFF)