Improve makefiles

Added the use of the $(MAKE) variable to support 'gnumake'.
Fixed an issue with some make compile rule and the -o option.
All targets are removed from the build directory when running 'make clean'.

Makefile

@@ -1,10 +1,10 @@
-all: 
+all:
 	mkdir -p build
-	cd gtest; make all
-	cd test; make all
-	cd examples; make all
+	cd gtest; $(MAKE) all
+	cd test; $(MAKE) all
+	cd examples; $(MAKE) all
 
 clean: 
-	cd gtest; make clean
-	cd test; make clean
-	cd examples; make clean
+	cd gtest; $(MAKE) clean
+	cd test; $(MAKE) clean
+	cd examples; $(MAKE) clean

examples/Makefile

@@ -1,7 +1,7 @@
 all: 
-	cd embedded_ui; make all
-	cd driver_testing; make all
+	cd embedded_ui; $(MAKE) all
+	cd driver_testing; $(MAKE) all
 
 clean: 
-	cd embedded_ui; make clean
-	cd driver_testing; make clean
+	cd embedded_ui; $(MAKE) clean
+	cd driver_testing; $(MAKE) clean

examples/driver_testing/Makefile

@@ -30,10 +30,8 @@ clean:
 	@echo "    rm -f     *~"
 	rm -f *~
 	@echo "Removing programs"
-	@echo "    rm -f     "$(C_PROGNAME)
-	rm -f $(C_PROGNAME)
-	@echo "    rm -f     "$(CPP_PROGNAME) $(TEMPLATE_PROGNAME)
-	rm -f $(CPP_PROGNAME) $(TEMPLATE_PROGNAME)
+	@echo "    rm -f     $(CPP_PROGNAME_NOFFF) $(CPP_PROGNAME_FFF) $(TEMPLATE_PROGNAME)"
+	rm -f $(CPP_PROGNAME_NOFFF) $(CPP_PROGNAME_FFF) $(TEMPLATE_PROGNAME)
 
 
 $(BUILD_DIR)/%.o: %.c

gtest/Makefile

@@ -10,7 +10,7 @@ SOURCES=gtest-all.cc gtest-main.cc
 $(BUILD_DIR)/%.o: %.cc
 	@echo 'Building file: $<'
 	@echo 'Invoking: GCC C++ Compiler'
-	g++ -I../ -O0 -g3 -Wall -c -o"$@" "$<"
+	g++ -I../ -O0 -g3 -Wall -c -o "$@" "$<"
 	@echo 'Finished building: $<'
 	@echo ' '
 

test/Makefile

@@ -32,14 +32,14 @@ all: $(FFF_TEST_CPP_TARGET) $(FFF_TEST_C_TARGET) $(FFF_TEST_GLOBAL_C_TARGET) $(F
 $(BUILD_DIR)/%.o: %.cpp
 	@echo 'Building file: $<'
 	@echo 'Invoking: GCC C++ Compiler'
-	g++ -I../ -O0 -g3 -Wall -c -o"$@" "$<"
+	g++ -I../ -O0 -g3 -Wall -c -o "$@" "$<"
 	@echo 'Finished building: $<'
 	@echo ' '
 
 $(BUILD_DIR)/%.o: %.c
 	@echo 'Building file: $<'
 	@echo 'Invoking: GCC C Compiler'
-	gcc -I../ -O0 -g3 -Wall -std=c99 -c -o"$@" "$<"
+	gcc -I../ -O0 -g3 -Wall -std=c99 -c -o "$@" "$<"
 	@echo 'Finished building: $<'
 	@echo ' '
 
@@ -75,6 +75,7 @@ $(FFF_TEST_GLOBAL_CPP_TARGET): $(FFF_TEST_GLOBAL_CPP_OBJS)
 
 # Other Targets
 clean:
-	-$(RM) $(FFF_TEST_CPP_OBJS) $(FFF_TEST_GLOBAL_C_OBJS) $(FFF_TEST_C_OBJS) $(FFF_TEST_CPP_TARGET) $(FFF_TEST_C_TARGET) $(FFF_TEST_GLOBAL_C_TARGET)
+	-$(RM) $(FFF_TEST_CPP_OBJS) $(FFF_TEST_GLOBAL_C_OBJS) $(FFF_TEST_C_OBJS) \
+		$(FFF_TEST_CPP_TARGET) $(FFF_TEST_C_TARGET) $(FFF_TEST_GLOBAL_CPP_TARGET) $(FFF_TEST_GLOBAL_C_TARGET)
 	-@echo ' '