base-files: handle packages alternatives when apk removes packages

On commit 3010ab8 ("base-files: add update_alternatives function") was
implemented the function to handle ALTERNATIVES when using APK (OPKG
handle it internally) but in commit bcc6415 ("base-files: add
compatibility for APK and OPKG") was only called when adding a package,
so call it also when removing packages.

While we are here, check for a more specific *.alternatives files instead
of *.list, and remove redundant "filelist" variable definition.

Fixes: bcc6415 ("base-files: add compatibility for APK and OPKG")
Fixes: https://github.com/openwrt/openwrt/issues/19090
Fixes: https://github.com/openwrt/openwrt/issues/16991
Reported-and-tested-by: Eric Fahlgren <[email protected]>
Signed-off-by: Mario Andrés Pérez <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/19093
Signed-off-by: Robert Marko <[email protected]>

package/base-files/files/lib/functions.sh

@@ -216,6 +216,10 @@ default_prerm() {
 	local filelist="${root}/usr/lib/opkg/info/${pkgname}.list"
 	[ -f "$root/lib/apk/packages/${pkgname}.list" ] && filelist="$root/lib/apk/packages/${pkgname}.list"
 
+	if [ -e "$root/lib/apk/packages/${pkgname}.alternatives" ]; then
+		update_alternatives remove "${pkgname}"
+	fi
+
 	if [ -f "$root/usr/lib/opkg/info/${pkgname}.prerm-pkg" ]; then
 		( . "$root/usr/lib/opkg/info/${pkgname}.prerm-pkg" )
 		ret=$?
@@ -352,8 +356,7 @@ default_postinst() {
 		add_group_and_user "${pkgname}"
 	fi
 
-	if [ -e "${root}/lib/apk/packages/${pkgname}.list" ]; then
-		filelist="${root}/lib/apk/packages/${pkgname}.list"
+	if [ -e "${root}/lib/apk/packages/${pkgname}.alternatives" ]; then
 		update_alternatives install "${pkgname}"
 	fi