* common/call-gpg.c (_gpg_encrypt, _gpg_decrypt): Simply, use
gnupg_create_pipe.
* tests/gpgscm/ffi.c (do_inbound_pipe): Likewise.
* common/exechelp.h (gnupg_create_inbound_pipe): Use gnupg_fd_t
for native pipe descriptor and don't expose other end of pipe.
(gnupg_create_outbound_pipe): Ditto.
* common/exechelp-posix.c (create_pipe_and_estream): Clean up.
(gnupg_create_inbound_pipe): Fail if R_FD or R_FP is NULL.
(gnupg_create_outbound_pipe: Ditto.
* common/exechelp-w32.c (create_pipe_and_estream): Clean up.
(gnupg_create_inbound_pipe): Fail if R_FD or R_FP is NULL.
(gnupg_create_outbound_pipe: Ditto.
(gnupg_create_pipe): Move the code from original
create_pipe_and_estream to call _open_osfhandle.
* common/exectool.c (gnupg_exec_tool_stream): Follow the change of
API.
* kbx/kbx-client-util.c (prepare_data_pipe): Likewise.