errno printing functions to use it.
(werror_format): New function.
(fatal): Compile time flag to display pid and hang, instead of
aborting. Useful for debugging.

Rev: src/adns.c:1.3
Rev: src/client.c:1.141
Rev: src/daemon.c:1.8
Rev: src/io.c:1.174
Rev: src/lock_file.c:1.6
Rev: src/lsh-decode-key.c:1.17
Rev: src/lsh-export-key.c:1.15
Rev: src/lsh-make-seed.c:1.9
Rev: src/lsh-writekey.c:1.26
Rev: src/lsh.c:1.166
Rev: src/lshd.c:1.144
Rev: src/reaper.c:1.24
Rev: src/server.c:1.70
Rev: src/server_pty.c:1.23
Rev: src/server_session.c:1.94
Rev: src/server_x11.c:1.9
Rev: src/ssh1_fallback.c:1.13
Rev: src/suspend.c:1.2
Rev: src/unix_interact.c:1.16
Rev: src/unix_process.c:1.11
Rev: src/unix_random.c:1.11
Rev: src/unix_user.c:1.54
Rev: src/werror.c:1.67