Add install/uninstall to Makefile

Makefile

@@ -1,6 +1,6 @@
 CXX ?= c++
-CPPFLAGS ?= -O2
-CPPFLAGS += -Wall 			\
+CXXFLAGS ?= -O2
+CXXFLAGS += -Wall 			\
 	    -Wextra			\
 	    -pipe			\
 	    -Wmissing-declarations	\
@@ -20,6 +20,7 @@ SOURCES =	main.cpp	\
 
 OBJECTS = $(SOURCES:.cpp=.o)
 EXECUTABLE = chess
+INSTALLDIR := $(DESTDIR)/usr/bin
 
 all: $(SOURCES) $(EXECUTABLE)
 
@@ -29,10 +30,17 @@ $(EXECUTABLE): $(OBJECTS)
 
 .cpp.o:
 	@echo '  CC  $@'
-	@$(CXX) $(CPPFLAGS) -c $< -o $@
+	@$(CXX) $(CXXFLAGS) -c $< -o $@
 
 clean:
 	rm -rf $(OBJECTS) $(EXECUTABLE)
 
 distclean:
 	rm -rf $(OBJECTS)
+
+install:
+	install -m755 -D $(EXECUTABLE) "$(INSTALLDIR)/$(EXECUTABLE)"
+
+uninstall:
+	rm -f "$(INSTALLDIR)/$(EXECUTABLE)"
+