Cycles: Pack kernel textures into buffers for OpenCL

Image textures were being packed into a single buffer for OpenCL, which
limited the amount of memory available for images to the size of one
buffer (usually 4gb on AMD hardware). By packing textures into multiple
buffers that limit is removed, while simultaneously reducing the number
of buffers that need to be passed to each kernel.

Benchmarks were within 2%.

Fixes T51554.

Differential Revision: https://developer.blender.org/D2745

intern/cycles/kernel/split/kernel_data_init.h

@@ -52,9 +52,7 @@ void KERNEL_FUNCTION_FULL_NAME(data_init)(
         ccl_global uint *rng_state,
 
 #ifdef __KERNEL_OPENCL__
-#define KERNEL_TEX(type, ttype, name)                                   \
-        ccl_global type *name,
-#include "kernel/kernel_textures.h"
+		KERNEL_BUFFER_PARAMS,
 #endif
 
         int start_sample,
@@ -100,9 +98,8 @@ void KERNEL_FUNCTION_FULL_NAME(data_init)(
 	split_data_init(kg, &kernel_split_state, num_elements, split_data_buffer, ray_state);
 
 #ifdef __KERNEL_OPENCL__
-#define KERNEL_TEX(type, ttype, name) \
-	kg->name = name;
-#include "kernel/kernel_textures.h"
+	kernel_set_buffer_pointers(kg, KERNEL_BUFFER_ARGS);
+	kernel_set_buffer_info(kg);
 #endif
 
 	int thread_index = ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0);