confd: add error handling in case of failed bootstrap or load

- New script 'error' that can be overridden by a br2-external
 - Call 'error' if YANG model bootstap or factory-config.gen fails
 - Call 'error' if loading startup-config or failure-config fails

The 'error' script calls syslog¹ to log the error messge:

    The device has reached an unrecoverable error, please RMA.
____
¹ to get a timestamp log message, and send remote in case a
  br2-external has somehow hard-coded network for remote syslog

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

package/confd/sysrepo.conf

@@ -1,7 +1,11 @@
 #set DEBUG=1
 
-run name:bootstrap log:prio:user.notice <pid/syslogd> \
-	[S] /usr/libexec/confd/bootstrap -- Bootstrapping YANG datastore
+run name:bootstrap log:prio:user.notice norestart <pid/syslogd> \
+	[S] /usr/libexec/confd/bootstrap \
+	-- Bootstrapping YANG datastore
+
+run name:error :1 log:console norestart if:<run/bootstrap/failure> \
+	[S] /usr/libexec/confd/error --
 
 service name:sysrepo log <pid/syslogd> \
 	[S12345789] sysrepo-plugind -f -p /run/sysrepo.pid -n -v3 -- Configuration daemon
@@ -16,6 +20,9 @@ run name:failure log:prio:user.critical norestart if:<run/startup/failure> \
 	[S] <pid/sysrepo> /usr/libexec/confd/load failure-config \
 	-- Loading failure-config
 
+run name:error :2 log:console norestart if:<run/startup/failure> \
+	[S] /usr/libexec/confd/error --
+
 service name:netopeer log \
 	[12345789] <pid/sysrepo> netopeer2-server -F -t 60 \
 	-- NETCONF server

src/confd/Makefile.am

@@ -1,6 +1,5 @@
-SUBDIRS             = src yang share
+SUBDIRS             = bin share src yang
 dist_doc_DATA       = README.md LICENSE
 dist_sysconf_DATA   = confdrc
-pkglibexec_SCRIPTS  = $(wildcard bin/*)
 DISTCLEANFILES      = *~ *.d
 ACLOCAL_AMFLAGS     = -I m4

src/confd/bin/Makefile.am

@@ -0,0 +1,2 @@
+pkglibexec_SCRIPTS  = bootstrap error load \
+		      gen-hostkeys gen-hostname gen-interfaces

src/confd/bin/error

@@ -0,0 +1,5 @@
+#!/bin/sh
+# Override using an overlay in your br2-external to change the behavior
+
+logger -sik -p user.error "The device has reached an unrecoverable error, please RMA."
+exec sleep infinity

src/confd/configure.ac

@@ -5,6 +5,7 @@ AM_SILENT_RULES(yes)
 
 AC_CONFIG_FILES([
 	Makefile
+	bin/Makefile
 	share/Makefile
 	share/factory.d/Makefile
 	share/failure.d/Makefile