Temporarily Revert "[mlir] Add padding to 1-D Vector in CRunnerUtils.h"

as it broke the Werror build:

.../sources/llvm-project/mlir/include/mlir/ExecutionEngine/CRunnerUtils.h:85:16: error: zero size arrays are an extension [-Werror,-Wzero-length-array]
  char padding[detail::nextPowerOf2<sizeof(T[Dim])>() - sizeof(T[Dim])];
               ^~~~~~~~~~~~~~~

This reverts commit 78f9e5d0.