Add syslog and fatal signal handler feature

I see random ENOTCONN failures in xfstest generic/013 and generic/014
in my branch, but earliest on the 2nd run - takes ~12hours to get
the issue, but then there are no further information logged.
ENOTCONN points to a daemon crash - I need backtraces and a core dump.

This adds optional handling of fatal signals to print a core dump
and optional syslog logging with these new public functions:

fuse_set_fail_signal_handlers()
    In addition to the existing fuse_set_signal_handlers(). This is not
    enabled together with fuse_set_signal_handlers(), as it is change
    in behavior and file systems might already have their own fatal
    handlers.

fuse_log_enable_syslog
    Print logs to syslog instead of stderr

fuse_log_close_syslog
    Close syslog (for now just does closelog())

Code in fuse_signals.c is also updated, to be an array of signals,
and setting signal handlers is now down with a for-loop instead
of one hand coded set_one_signal_handler() per signal.

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/fuse_versionscript b/lib/fuse_versionscript
index 1058372..14cbca1 100644
--- a/lib/fuse_versionscript
+++ b/lib/fuse_versionscript
@@ -198,6 +198,9 @@ FUSE_3.17 {
 		fuse_passthrough_close;
 		fuse_session_custom_io_30;
 		fuse_session_custom_io_317;
+		fuse_set_fail_signal_handlers;
+		fuse_log_enable_syslog;
+		fuse_log_close_syslog;
 } FUSE_3.12;
 
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