VAX: Remove unused register allocation from QMATH DImode add/sub handler

VAX: Remove unused register allocation from QMATH DImode add/sub handler

An allocation is made for a temporary register, however it is unneeded,
as actually explained in the comment preceding the conditional block in
question, and consequently never used, so remove it.  The `temp' rtx is
already used elsewhere in the function, which is possibly why this dead
assignment has not been warned about.

	gcc/
	* config/vax/vax.c (vax_expand_addsub_di_operands): Remove
	unused register allocation.