enable flto link time optimization

CMakeLists.txt

@@ -15,7 +15,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/")
 set(EXECUTABLE_OUTPUT_PATH "${CMAKE_BINARY_DIR}")
 
 # set compiler flags, see http://stackoverflow.com/questions/7724569/debug-vs-release-in-cmake
-set(CMAKE_CXX_FLAGS                "-Ofast -fno-signed-zeros -fno-trapping-math -Wall -Wno-format-extra-args -Wextra -Wformat-nonliteral -Wformat-security -Wformat=2 -Wextra -Wno-implicit-fallthrough -pedantic -Wno-keyword-macro")
+set(CMAKE_CXX_FLAGS                "-Ofast -fno-signed-zeros -fno-trapping-math -Wall -Wno-format-extra-args -Wextra -Wformat-nonliteral -Wformat-security -Wformat=2 -Wextra -Wno-implicit-fallthrough -pedantic -Wno-keyword-macro -flto=auto")
 set(CMAKE_CXX_FLAGS_SANITIZE       "-Og -g -fsanitize=address -fsanitize=leak -fsanitize=undefined -DLOGLEVEL=3 -DPFAEDLE_DBG=1")
 set(CMAKE_CXX_FLAGS_PROFILE        "-g -pg -DLOGLEVEL=3 -DPFAEDLE_DBG=1")
 set(CMAKE_CXX_FLAGS_DEBUG          "-Og -g -DLOGLEVEL=3 -DPFAEDLE_DBG=1")