We have a similar code pattern in darwin-c.c to one in c-pragmas
(most likely a cut & paste) with a struct type used locally to the
TU. With C++ we need to rename the type to avoid an ODR violation.
gcc/ChangeLog:
* config/darwin-c.c (struct f_align_stack): Rename
to type from align_stack to f_align_stack.
(push_field_alignment): Likewise.
(pop_field_alignment): Likewise.