Update submodule libs/cuda_wrapper

* libs/cuda-wrapper 6f4c477...088a11c (2):
  > texture: replace private reference by pointer
  > cuda_wrapper: disable warning for CUDA 5.5 headers
numeric.blas: disable warning for CUDA 5.5 headers

Clang ≥ 3.3 emits a warning for CUDA 5.5 headers:

    /usr/local/cuda-5.5/include/cuda_runtime.h:225:33: warning: function
    'cudaMallocHost' is not needed and will not be emitted
    [-Wunneeded-internal-declaration]
particle: mark auxiliary variables dirty separately from the force

Introduce a new function to particle mark_aux_dirty() and set
aux_dirty_ = false only in this function, not automatically with a dirty
force. This allows the force modules to inform the particle module about
the auxiliary variables state independently from the force.