Add BIND BUFFER modifier to allow binding OPENCL-C arguments

[dj2]

Something along the lines of:

SHADER opencl-c my_kernel CLSPV
kernel void foo(global int4* in, global int4* out, int z) {
  out[z] = in[z];
END
BUFFER in_buf TYPE int4 DATA
7 4 2 3
END
BUFFER out_buf TYPE int4 SIZE 1

PIPELINE my_pipeline
  ATTACH my_kernel
  BIND BUFFER foo OPENCL-C KERNEL in_buf ARG in
  BIND BUFFER foo OPENCL-C KERNEL out_buf ARG out
END
RUN my_pipeline
EXPECT out_buf IDX 0 EQ 7 4 2 3

This must also correctly detect ubo vs ssbo. The descriptorSet/Binding should be determined by the data provided by the CLSPV compiler.

[dj2]

@alan-baker does the above make sense from a test perspective?

[alan-baker]

Having some way to specify compiler options would be very useful. Being able to run the test with a series of different compiler options would be really useful too.

[dj2]

Filed #433 for compiler options