Related to #2142, according to the work plan extended `CBasicTestStore`
with support for `atomic_half`.
Optimization remark: in tests related to `CBasicTestStore` kernel source
code is mostly composed with arguments following similar pattern:
`__kernel void test_atomic_kernel(uint threadCount, uint numDestItems,
__global int *finalDest, __global int *oldValues, volatile __local
atomic_int *destMemory)`
`oldValues` buffer is initialized with a host pointer, after kernel
execution it is read back to the host pointer but it is unused in
neither of the kernels I verified.
* Change setup code in `KernelCode()` to use `_explicit` builtin
variants that are common to both OpenCL-2.X and OpenCL-3.0.
* Only test optional supported builtin variants (`_explicit` signature
memory_order/scope) for OpenCL-3.0.
* Disable program scope global variable and generic address space tests
for a OpenCL-3.0 driver which does not optionally support these
features.
* Test minimum memory consistency capabilities for a device reporting >= 3.0.
Skip tests where unsupported memory consistency capabilities are being requested.
* Pass nullptr as program build option.
Allows the CTS framework to select an appropriate CL C version.
* Removed redundant braces.
