make-array with initial-contents in gcl is slow

In gcl make-array with :initial-contents from a list
is poorly implemented in that the copying is O(n^2).
A test on one machine shows that initializing a
list of length of 5 10^4 takes 1 minute in gcl and a few ms in sbcl.

This potentially affects some code in the share directory.

The relevant part of the gcl code in make-array is:

((= (length dimensions) 1)
	 (let ((x (si:make-vector element-type (car dimensions)
	                          adjustable fill-pointer
	                          displaced-to displaced-index-offset
	                          static initial-element)))
	   (when initial-contents-supplied-p
		 (do ((n (car dimensions))
		      (i 0 (1+ i)))
		     ((>= i n))
		   (declare (fixnum n i))
		   (si:aset x i (elt initial-contents i))))
	   x))

The following passed a quick test:

((= (length dimensions) 1)
	 (let ((x (si:make-vector element-type (car dimensions)
	                          adjustable fill-pointer
	                          displaced-to displaced-index-offset
	                          static initial-element)))
	   (when initial-contents-supplied-p
             (if (listp initial-contents)
                 (do ( (e initial-contents (cdr e))
                        (i 0 (1+ i)))
                     ((null e))
                   (declare (fixnum i))
                   (si:aset x i (car e)))
               (do ((n (car dimensions))
                    (i 0 (1+ i)))
                   ((>= i n))
                 (declare (fixnum n i))
                 (si:aset x i (elt initial-contents i)))))
           x))

-- John Lapeyre