PR25651, objcopy SIGSEGV in copy_object

PR25651, objcopy SIGSEGV in copy_object

With the right set of options, the second block of code dealing with
padding can see a different section count.  So don't use the new count.
Since I was editing those lines, I've also changed the code allocating
arrays a little.
    array = malloc (n * sizeof (*array));
for an array of ints is just better than
    array = malloc (n * sizeof (int));
It's easier to write correctly in the first place and more robust
against code changes that might modify the array element type.

	PR 25651
	* objcopy.c (copy_object): Test "gaps" not gap_fill_set or
	pad_to_set on second block of code dealing with padding.
	Replace "c" with "num_sec" and don't recalculate number of
	sections on second block.  Size arrays using sizeof (element)
	rather than sizeof (element type).