Fix PR47654: Loop blocking should strip-mine at least two loops.

Fix PR47654: Loop blocking should strip-mine at least two loops.

	PR tree-optimization/47654
	* graphite-blocking.c (pbb_strip_mine_time_depth): Do not return bool.
	(lst_do_strip_mine_loop): Return an int.
	(lst_do_strip_mine): Same.
	(scop_do_strip_mine): Same.
	(scop_do_block): Loop blocking should strip-mine at least two loops.
	* graphite-interchange.c (lst_interchange_select_outer): Return an int.
	(scop_do_interchange): Same.
	* graphite-poly.h (scop_do_interchange): Update declaration.
	(scop_do_strip_mine): Same.

	* gcc.dg/graphite/block-pr47654.c: New.

From-SVN: r175861