Author: Matthijs Kooijman <matthijs@stdin.nl>
Description: Pass CPPFLAGS (C preprocessor flags) from the environment to the C++ compiler.
 This allows all hardening options to be enabled.

--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,7 @@
 objs/%.o: src/%.cpp
 	$(Q)mkdir -p objs
 	@echo '[CPP] $@'
-	$(Q)$(CXX) $(CXXFLAGS) -c -o $@ $<
+	$(Q)$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
 
 $(CATCODEC): $(OBJS:%=objs/%)
 	@echo '[LINK] $@'