prog/encodingexec: pad data args with zero bytes
prog/encodingexec: pad data args with zero bytes

We must pad data arguments with known values when serializing
them into the given destination buffer because it could
be reused and contain random bytes from previous use.

Signed-off-by: Alexander Egorenkov <91da4175525e9dfd14770d775671f3c95d603858@ibm.com>

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