PR debug/78839
	* dwarf2out.c (field_byte_offset): Restore the
	PCC_BITFIELD_TYPE_MATTERS behavior for INTEGER_CST DECL_FIELD_OFFSET
	and DECL_FIELD_BIT_OFFSET.  Use fold_build2 instead of build2 + fold.
	(analyze_variants_discr, gen_variant_part): Use fold_build2 instead
	of build2 + fold.

From-SVN: r244545