c++/10481: Invalid use of non-static data member causes ICE.

[Jonathan Wakely]

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10481

This is a regression since 3.2.1, which gave the following diagnostic
for B::f():

ice.cc: In member function `void B::f(const A&) const':
ice.cc:18: type `A' is not a base type for type `B'