No explicit coverage of using multiple kernels created from the same source program with different builds

[kpet]

OpenCL programs can be built multiple times, with different options that can affect the behaviour of the kernels. We do not, AFAICT, test this explicitly in the CTS.

Suggested test:

• Create two buffers
• Create a program from source (the source contains a single kernel that writes a value defined by a preprocessor macro into a buffer)
• Build the program, setting the macro to one value
• Create a kernel from the program
• Enqueue the kernel, with buffer 1 as a parameter
• Build the program again, setting the macro to a different value
• Create a kernel from the program
• Enqueue the kernel, with buffer 2 as a parameter
• Call clFinish on the queue
• Check that both buffers contain different values and the right value for each kernel

Also consider adding a variant using clCompileProgram/clLinkProgram.