Fix for <http://rsync.samba.org/cgi-bin/rsync/incoming?id=3750>

temp files must be opened through do_open so that binary modes is used
on cygwin.  (Chris Boucher)

syscall.c

@@ -132,7 +132,7 @@ int do_mkstemp(char *template, mode_t perms)
 	}
 #else
 	if (!mktemp(template)) return -1;
-	return open(template, O_RDWR|O_EXCL|O_CREAT, perms);
+	return do_open(template, O_RDWR|O_EXCL|O_CREAT, perms);
 #endif
 }