I have created a small patch that makes possible to compile pgsql on newer

Cygwin snapshots (tested on 990115 which is recommended to use - it fixes
some errors in B20.1)

And I have another patch for including <sys/ipc.h> before <sys/sem.h> in
backend/storage/lmgr/proc.c - it is required due the design of cygipc
headers

                        Dan