VAX: Correct issues with commented-out insns

VAX: Correct issues with commented-out insns

Correct issues with commented-out insns, which fail to build if enabled:

.../gcc/config/vax/vax.md:503:1: repeated operand number 1
.../gcc/config/vax/vax.md:503:1: repeated operand number 2

and then when the issue with the repeated operands has been corrected:

.../gcc/config/vax/vax.md:107:1: destination operand 0 allows non-lvalue
.../gcc/config/vax/vax.md:503:1: destination operand 0 allows non-lvalue
.../gcc/config/vax/vax.md:503:1: destination operand 3 allows non-lvalue
.../gcc/config/vax/vax.md:744:1: destination operand 0 allows non-lvalue

Fix the RTL with the repeated operands and change the relevant output
operand predicates not to allow immediates.

Also emit MOVO rather than MOVH assembly instruction with the `movti'
insn so that the condition codes are set according to the integer rather
than floating-point interpretation of the datum moved, as expected with
the operation associated with the pattern.

Finally give `*amulsi4' a name, for easier reference here and elsewhere.

We may eventually want to have some of these insns enabled at `-Os'.

	gcc/
	* config/vax/vax.md (movti): Fix output predicate.  Emit `movo'
	rather than `movh'.
	(divmoddisi4): Fix output predicates, correct RTL.
	(*amulsi4): Name insn.  Fix output predicate.