Silence clang++ warnings

Using defined(foo) in a macro expansion is undefined.

external/easylogging++/easylogging++.h

@@ -290,7 +290,11 @@ ELPP_INTERNAL_DEBUGGING_OUT_INFO << ELPP_INTERNAL_DEBUGGING_MSG(internalInfoStre
 #define ELPP_VARIADIC_TEMPLATES_SUPPORTED \
 (ELPP_COMPILER_GCC || ELPP_COMPILER_CLANG || ELPP_COMPILER_INTEL || (ELPP_COMPILER_MSVC && _MSC_VER >= 1800))
 // Logging Enable/Disable macros
-#define ELPP_LOGGING_ENABLED (!defined(ELPP_DISABLE_LOGS))
+#ifdef ELPP_DISABLE_LOGS
+#  define ELPP_LOGGING_ENABLED 0
+#else
+#  define ELPP_LOGGING_ENABLED 1
+#endif
 #if (!defined(ELPP_DISABLE_DEBUG_LOGS) && (ELPP_LOGGING_ENABLED))
 #  define ELPP_DEBUG_LOG 1
 #else