Use more efficient alignment in ggc

Use more efficient alignment in ggc

Jakub had some concerns about the performance of page alignments in
ggc-page, which use a hardware division instructions currently.
This patch changes them all to use a new PAGE_ALIGN macro, which
exploits that pages are a power of two.

gcc/:
2011-10-21  Andi Kleen  <ak@linux.intel.com>

	* ggc-page (PAGE_ALIGN): Add.
	(alloc_page, ggc_pch_total_size, ggc_pch_this_base, ggc_pch_read):
	Replace ROUND_UP with PAGE_ALIGN.

From-SVN: r180650