Re-enable OpenCL FiniteDiff tests once LLVM SPIR-V backend bug is fixed #409
Description
The gpu_kernel_de/finite_diff.jl tests are currently skipped on the OpenCL backend (PR #407) due to a bug in the LLVM SPIR-V backend (SPIRV_LLVM_Backend_jll).
The backend crashes when compiling functions that return SMatrix{1,1,Float32} (lowered to [1 x float] in LLVM IR), miscompiling the return type to i32 and aborting with LLVM ERROR: Broken function found, compilation aborted!.
Tracked upstream: JuliaGPU/OpenCL.jl#422
Once that issue is resolved, the skip in test/runtests.jl should be removed to re-enable the FiniteDiff tests on OpenCL.