* machmode.h (mode_for_size, smallest_mode_for_size): SIZE now signed.
	* stor-layout.c (mode_for_size, smallest_mode_for_size): Likewise.
	(mode_for_size_tree): New function.
	(layout_decl, layout_type): Call it and clean up BLKmode checks.
	* tree.h (mode_for_size_tree): New declaration.

From-SVN: r32326