HDF5PLUGIN_SSE2=False does not disable SSE2 for the bitshuffle filter

[t20100]

SSE2 is enabled by default on gcc/clang and msvc.

Setting HDF5PLUGIN_SSE2=False only disable using it for blosc and blosc2 (thanks to the SHUFFLE_SSE2_ENABLED macro), but the __SSE2__ macro is still defined and so the bitshuffle filter will compile with SSE2 support.

Not sure it is much of an issue as wheels and conda builds are done with HDF5PLUGIN_SSE2=True