evas vg shape: gradient taken from the proper source

evas vg shape: gradient taken from the proper source

When a shape with the gradient is duplicated, the gradient
adr was taken from the source obj instead of from the target
of the duplication.
In TVG, when a shape is duplicated all its properties, like grad,
are duplicated as well. EFL created independently a new gradient,
which has to be relased first and replaced by the one created
in TVG.

Change-Id: I0848b0591671b6e69148b0d248a0ba0c8bd66726