Also fixed a bug where the same key.pkl file could be loaded multiple times.

We should use the linker=c|py_nogc flags.
Remove reference to FAST_RUN_NOGC that never existed.

PROFILE_MODE a suggestion message says you should compile the function in a
different mode like for e.g. FAST_RUN_NOGC. When you try to compile in this
mode, you get an error saying there is no such mode .. though there actually
is.

tensor.as_tensor_variable on inputs of x, but I should do that only if they
where numpy.ndarrays (maybe other types) .. because they could be random
states case in which tensor.as_tensor_variable fails.