Remove double assignment

The semantic match that finds this problem is follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r@
expression i,f;
position p1,p2;
@@
(
(<+...i++...+>) = ...;
|
(<+...++i...+>) = ...;
|
(<+...i--...+>) = ...;
|
(<+...--i...+>) = ...;
|
i = <+...f(...)...+>;
|
i@p1 = ...;
(
i = <+...i...+>;
|
i = <+...f(...)...+>;
|
i@p2 = ...;
)
)

@@
expression i;
position r.p1,r.p2;
@@

* i@p1 = ...;
i@p2 = ...;
// </smpl>

Change-Id: Ifacb878d58486f2645560592484ce24b2bc0bd6f
Reviewed-on: https://gerrit.libreoffice.org/9968
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>