This patch introduces "failure save". The syscall status is subset of
the saved failure, but the failure can be used also for non-syscall
issues.

* save SYS_* numbers rather than names for syscalls. It will make error
  generators more simple (just switch(cxt->failure_syscall))

* save hookset; it will be later used to call hookset specific error
  message generator

* optionally save "failure command", for example syscall sub-command (FSCONFIG_CMD_*) or
  some hook specific stuff

* optionally save "failure argument" as string (to make error messages
  more human friendly)

* use line and filename in debug message for failures

Note that the way how libmount uses syscall_status is not affected by
this patch, because this field is used by public API.

Signed-off-by: Karel Zak <kzak@redhat.com>

Signed-off-by: Karel Zak <kzak@redhat.com>

Signed-off-by: Karel Zak <kzak@redhat.com>

It helps to maintain mount syscall-specific error messages on place
where we use the syscalls.

Signed-off-by: Karel Zak <kzak@redhat.com>

Signed-off-by: Karel Zak <kzak@redhat.com>

Signed-off-by: Karel Zak <kzak@redhat.com>

Signed-off-by: Karel Zak <kzak@redhat.com>

Signed-off-by: Karel Zak <kzak@redhat.com>