build_patches: Remove additional config files preserved during upgrade

OpenWrt saves additional config (and other) files included with
list_changed_conffiles in /sbin/sysupgrade.

This is only active since openwrt-18.06, since before that it was
suppressed by missing opkg.

Since we expect to only save what is in sysupgrade.conf, remove
the additional file list (and thus regain pre-openwrt-18.06
behavior).

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

build_patches/openwrt/0001-sysupgrade-no-config-save.patch

@@ -3,18 +3,21 @@ Date: Sat, 8 Jul 2017 10:46:59 +0200
 Subject: sysupgrade no config save
 
 diff --git a/package/base-files/files/sbin/sysupgrade b/package/base-files/files/sbin/sysupgrade
-index b75bd097f3..ddcfcd74e4 100755
+index b75bd097f3..8ad778fd69 100755
 --- a/package/base-files/files/sbin/sysupgrade
 +++ b/package/base-files/files/sbin/sysupgrade
-@@ -118,7 +118,7 @@ list_changed_conffiles() {
+@@ -118,9 +118,9 @@ list_changed_conffiles() {
  add_uci_conffiles() {
  	local file="$1"
  	( find $(sed -ne '/^[[:space:]]*$/d; /^#/d; p' \
 -		/etc/sysupgrade.conf /lib/upgrade/keep.d/* 2>/dev/null) \
 +		/etc/sysupgrade.conf 2>/dev/null) \
  		-type f -o -type l 2>/dev/null;
- 	  list_changed_conffiles ) | sort -u > "$file"
+-	  list_changed_conffiles ) | sort -u > "$file"
++	  ) | sort -u > "$file"
  	return 0
+ }
+
 -- 
 2.11.0