cmake: add USE_COMPILER_BUILTINS CMake option

This introduces USE_COMPILER_BUILTINS CMake option. It is enabled
by default.

Disabling it is meant to test the unknown compiler code.

cmake/DaemonFlags.cmake

@@ -29,6 +29,15 @@ include(CheckCXXCompilerFlag)
 
 add_definitions(-DDAEMON_BUILD_${CMAKE_BUILD_TYPE})
 
+option(USE_COMPILER_BUILTINS "Enable usage of compiler builtins" ON)
+
+if (USE_COMPILER_BUILTINS)
+    add_definitions(-DDAEMON_USE_COMPILER_BUILTINS=1)
+    message(STATUS "Enabling compiler builtins")
+else()
+    message(STATUS "Disabling compiler builtins")
+endif()
+
 # Set flag without checking, optional argument specifies build type
 macro(set_c_flag FLAG)
     if (${ARGC} GREATER 1)

src/common/Compiler.h

@@ -95,7 +95,7 @@ int CountTrailingZeroes(unsigned long long x);
 #endif
 
 // GCC and Clang
-#if defined(__GNUC__)
+#if defined(DAEMON_USE_COMPILER_BUILTINS) && defined(__GNUC__)
 
 // Emit a nice warning when a function is used
 #define DEPRECATED __attribute__((__deprecated__))
@@ -180,7 +180,7 @@ See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0627r0.pdf */
 #endif
 
 // Microsoft Visual C++
-#elif defined(_MSC_VER)
+#elif defined(DAEMON_USE_COMPILER_BUILTINS) && defined(_MSC_VER)
 
 // Disable some warnings
 #pragma warning(disable : 4100) // unreferenced formal parameter