[SYCL] Fix launching a kernel with a default constructed local accessor

[jzc]

According to 4.7.6.11.1. Interface for local accessors, passing a default constructed local accessor to a kernel function is allowed, as long as no accesses to the data elements are made.

When default constructing a local_accessor, it will default construct its local_accessor_base

llvm/sycl/include/sycl/accessor.hpp

Lines 2803 to 2805 in 3f841ff

	local_accessor_base()
	: detail::LocalAccessorBaseHost{/*Size*/ sycl::range<3>{0, 0, 0},
	/*Dims*/ 0, /*ElemSize*/ sizeof(DataT)} {}

leading its LocalAccessorImplHost to be constructed with MDims == 0. When setting the kernel arguments corresponding to the local accessor, this caused piKernelSetArg to be called with arg_size == 0, which then causes an error. This PR fixes this by checking if MDims would be 0 and then setting an appropriate value.

[jzc]

-O0 is necessary; on higher levels of optimization, an error does not occur because of dead argument elimination of the local_accessor.

[AlexeySachkov]

This comment should be moved to the test itself