cp:
	* class.c (mark_primary_virtual_base): Don't adjust base
	offsets here.
	(dfs_unshared_virtual_bases): Adjust them here.
	(mark_primary_bases): Explain why we adjust at the end.
testsuite:
	* g++.dg/abi/vbase8-21.C: New test.

From-SVN: r44425