w32ce: Adjust to changed API and make it build again.

* src/system-w32ce.c (__assuan_write, __assuan_recvmsg)
(__assuan_sendmsg, __assuan_waitpid): Make functions global.
* tests/ce-server.c: Fix syntax error (s/#else/#endif)

This patch fixes some cruft which has accidentally been introduced
over time. The code builds, but due to a lack of ready to use CE box,
I was not able to test it.