Lower the number of disk access: continuation

Fix tests

Fix DebugMode error introduced by recent changes in Scan

Local alloc elemwise2

Faster fft tests

[WIP] Do not run cudnn available on the default GPU.

Update the whitelist of flags passed directly to nvcc

Lock

fix lock clean up code when there is a bug. This could help following tests to restart in a good state.

instead of being passed to -Xlinker.
These are necessary to compile on Windows, at least in the case
where more than one version of visual studio's cl.exe are available.

COp conflict between old section markers and new section markers

There is still one problem in the tests to work out though so this is not ready to merge.

skip cudnn test if we can't use it.

Faster tests

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