Fix uninitialized field in expand_operand.

Commit g:f96bf49a added the target field to expand_operand.
But it leaves it uninitialized when doing a full initialization
inside create_expand_operand.  This fixes the problem and improves
the code generation inside create_expand_operand too.

ChangeLog:
* optabs.h (create_expand_operand): Initialize target field also.

gcc/ChangeLog

+2020-01-16  Andrew Pinski  <apinski@marvell.com>
+
+	* optabs.h (create_expand_operand): Initialize target field also.
+
 2020-01-16  Andre Vieira  <andre.simoesdiasvieira@arm.com>
 
 	PR tree-optimization/92429

gcc/optabs.h

@@ -78,6 +78,7 @@ create_expand_operand (class expand_operand *op,
 {
   op->type = type;
   op->unsigned_p = unsigned_p;
+  op->target = 0;
   op->unused = 0;
   op->mode = mode;
   op->value = value;