Align struct COrphan definition #9269

Since #8179 the struct COrphan definition gained an extra field. The mirrored definition in DoS_tests was not updated, however. This violates the C++ one definition rule.

Found using GCC 6.2.0, when compiling with -flto:

test/DoS_tests.cpp:29:8: warning: type 'struct COrphanTx' violates the C++ One Definition Rule [-Wodr]
 struct COrphanTx {
        ^
net_processing.cpp:52:8: note: a different type is defined in another translation unit
 struct COrphanTx {
        ^
net_processing.cpp:55:13: note: the first difference of corresponding definitions is field 'nTimeExpire'
     int64_t nTimeExpire;
             ^
net_processing.cpp:52:8: note: a type with different number of fields is defined in another translation unit
 struct COrphanTx {
        ^
test/DoS_tests.cpp:29:8: note: type 'struct COrphanTx' itself violate the C++ One Definition Rule
 struct COrphanTx {
        ^
net_processing.cpp:52:8: note: the incompatible type is defined here
 struct COrphanTx {
        ^

No way to test ?

I believe in practice it never matters, as the added field is in the last place, and the size of COrphan isn't used. However, it is technically undefined behaviour I think.

utACK 22970b0537c9b1747ab66760b8d528fb32848262

ACK 22970b0

Minor nit: change the comment: COrphan -> COrphanTx.

Looks like main is still not dead: https://github.com/bitcoin/bitcoin/pull/9269/commits/22970b0537c9b1747ab66760b8d528fb32848262#diff-eb50db371aa7bd12e62a13879bc661f7L25

;-)

nit: Maybe add a comment to the main definition to remind people to update this one? (ugly but...)

utACK.

Alternatively, we could just expose these functions from main.h, and not duplicate them at all...

Would prefer to not expose them from net_processing.h, even if duplicating them is really gross. Would prefer to add a comment instead.

Added a comment.

Adding fields to the end is harmless, a lot of software relies on that with ABIs.

But it makes sense to sync it anyhow, ACK