* autogen.sh: Add Option --build-w32.
* assuan-logging.c (_assuan_w32_strerror): New.
* assuan-defs.h (w32_strerror): new.
* assuan-pipe-connect.c (assuan_pipe_connect2, fix_signals):
Factored signal code out to new function.
(build_w32_commandline, create_inheritable_pipe): New.  Taken
from gnupg 1.9.
(assuan_pipe_connect2) [W32]: Implemented for W32.