re PR c++/64433 (Segmentation fault while compiling)
cp/
PR c++/64433
DR1658, DR1611
* init.c (emit_mem_initializers): Don't construct vbases of
abstract classes.
(push_base_cleanups): Don't push vbase cleanups for abstract class
when in C++14 mode.
* method.c (synthethesized_method_walk): Don't walk vbases of
abstract classes when in C++14 mode.