.noinit and .persistent alignment

It's more elegant to make the section match up with its "_start"
symbol.  We could align by setting the address of the section (by
using ALIGN before the colon), but this way we also set sh_addralign
to at least $ALIGNMENT.

	* scripttempl/elf.sc (.noinit, .persistent): Align the output
	section rather than using ". = ALIGN();" at the beginning.
	Set address to zero when not a final link.