Reintroduce though-to-be unused variable in correct place
Reintroduce though-to-be unused variable in correct place

The variable is a local variable for the i386 bignum assembly only;
introduce it as part of the start/finish macros.

It can be noted that the variable is initialize to 0 within MULADDC_INIT,
so there are no data dependencies across blocks of MULADDC_INIT/CORE/STOP.

Signed-off-by: Hanno Becker <4d488caff78d6184f59bbe6e137e34d4606b9fe8@arm.com>

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