VE kernels stdout isn't redirected

[efocht]

This leads to the failure of test/execution.jl testset "varargs":

@testset "varargs" begin
    function kernel(args...)
        VectorEngine.@veprint(args[2])
        return
    end

    _, out = @grab_output begin
        @veda kernel(1, 2, 3)
        synchronize()
    end
    @test out == "2"
end

The out content is always the empty string "". The correct output (2) is printed on the console.

[efocht]

The reason for this behavior is that Julia is able to temporarily reassign stdin/our/err descriptors. The VE kernel runs in a child process that inherits the original descriptors, these are not being reassigned by Julia. The child process is started when the VectorEngine module is loaded, therefore there is no chance for the child to see the re-assigned descriptors of the parent.
The problem is thus with ve-urpc vh_urpc_child_create() which would need to carefully connect the parent's descriptors with those of any of its children.