Makefile.am: Add timegm.cc to scriptindex_SOURCES to fix build on
platforms which don't provide timegm().
api/error.cc,generate-exceptions,net/remoteconnection.h: On
Windows, avoid defining EADDRINUSE, etc if they're already defined,
and use WSAE* constants un-negated, as they start from a high value
so won't collide with E* constants.