I wrote improved patch to remove the 'si_band'.  This patch modifies the 'n_in_sequence' to conform to the number of structure members.
And I tested manually for struct_siginfo.  struct_siginfo objects builds well.
That's all for now.

$ python3.4.exe
Python 3.4.3 (default, Mar  2 2015, 22:23:56)
[GCC 4.9.2] on cygwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import signal
>>> signal.struct_siginfo([1, 2, 3, 4, 5, 6])
signal.struct_siginfo(si_signo=1, si_code=2, si_errno=3, si_pid=4, si_uid=5, si_status=6)
>>> signal.sigwaitinfo({signal.SIGINT})
^C
signal.struct_siginfo(si_signo=2, si_code=6, si_errno=0, si_pid=3352, si_uid=1000, si_status=0)
>>> signal.alarm(1); signal.sigwaitinfo({signal.SIGALRM})
0
signal.struct_siginfo(si_signo=14, si_code=4, si_errno=0, si_pid=5816, si_uid=1000, si_status=1629189728)