systemd: Use overlay for specifying watchdog parameters

There's no reason to sed stuff. This way also makes it easier to support
running with empty /etc.

Change-Id: I16c0dba53682df574ee119951f47c7c6d4071d61
diff --git a/board/czechlight/common/overlay/usr/lib/systemd/system.conf.d/watchdog.conf b/board/czechlight/common/overlay/usr/lib/systemd/system.conf.d/watchdog.conf
new file mode 100644
index 0000000..3c8a109
--- /dev/null
+++ b/board/czechlight/common/overlay/usr/lib/systemd/system.conf.d/watchdog.conf
@@ -0,0 +1,3 @@
+[Manager]
+RuntimeWatchdogSec=60
+ShutdownWatchdogSec=60
diff --git a/board/czechlight/common/systemd-watchdog.sh b/board/czechlight/common/systemd-watchdog.sh
deleted file mode 100755
index 07ad9f0..0000000
--- a/board/czechlight/common/systemd-watchdog.sh
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/bin/bash
-
-set -eux
-
-sed -i -E "s/(#?)ShutdownWatchdogSec=(.*)/ShutdownWatchdogSec=60/" ${TARGET_DIR}/etc/systemd/system.conf
-sed -i -E "s/(#?)RuntimeWatchdogSec=(.*)/RuntimeWatchdogSec=60/" ${TARGET_DIR}/etc/systemd/system.conf
diff --git a/configs/czechlight_beaglebone_defconfig b/configs/czechlight_beaglebone_defconfig
index 7d7137f..97a7393 100644
--- a/configs/czechlight_beaglebone_defconfig
+++ b/configs/czechlight_beaglebone_defconfig
@@ -12,7 +12,7 @@
 BR2_TARGET_GENERIC_GETTY_PORT="ttyO0"
 # BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW is not set
 BR2_ROOTFS_OVERLAY="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/overlay/ $(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/beaglebone/overlay/"
-BR2_ROOTFS_POST_BUILD_SCRIPT="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/dhcp-network.sh $(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/systemd-watchdog.sh"
+BR2_ROOTFS_POST_BUILD_SCRIPT="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/dhcp-network.sh"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/beaglebone/post-image.sh"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
diff --git a/configs/czechlight_clearfog_defconfig b/configs/czechlight_clearfog_defconfig
index 05a738b..0ba21a4 100644
--- a/configs/czechlight_clearfog_defconfig
+++ b/configs/czechlight_clearfog_defconfig
@@ -13,7 +13,7 @@
 BR2_INIT_SYSTEMD=y
 # BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW is not set
 BR2_ROOTFS_OVERLAY="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/overlay/"
-BR2_ROOTFS_POST_BUILD_SCRIPT="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/common/systemd-watchdog.sh $(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/clearfog/post-build.sh"
+BR2_ROOTFS_POST_BUILD_SCRIPT="$(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/clearfog/post-build.sh"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
 BR2_ROOTFS_POST_SCRIPT_ARGS="-c $(BR2_EXTERNAL_CZECHLIGHT_PATH)/board/czechlight/clearfog/genimage.cfg"
 BR2_LINUX_KERNEL=y