allow to override the numpy include directory

Makefile

 CUDA_NDARRAY?=$(HOME)/cvs/lgcm/cuda_ndarray
+NUMPY_INCLUDE?=/usr/include/python2.6
 
 type_support.so : type_support.cu $(CUDA_NDARRAY)/cuda_ndarray.so
-	nvcc -g -shared -I$(CUDA_NDARRAY) -I$(CUDA_ROOT)/include -I/usr/include/python2.6 -o type_support.so -Xcompiler -fPIC type_support.cu -L$(CUDA_ROOT)/lib -L$(CUDA_NDARRAY) -lcuda_ndarray
+	nvcc -g -shared -I$(CUDA_NDARRAY) -I$(CUDA_ROOT)/include -I$(NUMPY_INCLUDE) -o type_support.so -Xcompiler -fPIC type_support.cu -L$(CUDA_ROOT)/lib -L$(CUDA_NDARRAY) -lcuda_ndarray
 
 clean : 
 	rm type_support.so