coccinelle: misc: semantic patch to delete overly complex return code processing

This semantic patch simplifies cases where the effect of the processing of
a function call's return code is just to return the result of the function
directly.  It may also delete a local return flag variable, if this is no
longer used.

This was proposed by Uwe Kleine-König.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>