Update Makefile with all and cuda stuff

Makefile

@@ -1,16 +1,19 @@
 
 LIBS = -l OpenCL
+FLAGS = -std=c++11 -O3
 
 PLATFORM = $(shell uname -s)
 ifeq ($(PLATFORM), Darwin)
 	LIBS = -framework OpenCL
 endif
 
+all: gpu-stream-ocl gpu-stream-cuda
+
 gpu-stream-ocl: ocl-stream.cpp
-	c++ $< -std=c++11 -o $@ $(LIBS)
+	c++ $< $(FLAGS) -o $@ $(LIBS)
 
 gpu-stream-cuda: cuda-stream.cu
-	nvcc $< -o $@
+	nvcc $< $(FLAGS) -o $@
 
 clean:
-	rm -f gpu-stream-ocl
+	rm -f gpu-stream-ocl gpu-stream-cuda