* tm.texi (Exception Region Output): Document
	DWARF_CIE_DATA_ALIGNMENT.
	* dwarf2out.c (DWARF_CIE_DATA_ALIGNMENT): Wrap definition in
	#ifndef.
	[ENABLE_CHECKING] (reg_save): Abort if offset is not a multiple of
	DWARF_CIE_DATA_ALIGNMENT.

From-SVN: r36935