update-kernel: Suggest user to not install if there aren't some external modules

Example of such module is zfs.

Signed-off-by: Vitaly Chikunov <vt@altlinux.org>

update-kernel

@@ -405,6 +405,7 @@ ALLNAMES=$(echo -n "$ALLMODULES" | sed "s/-$kernel_flavour#.*//;s/kernel-modules
 # - you cannot guess flavour from module package name;
 # - perhaps this will overwhelm user;
 # thus only two flavours should be checked - booted and the same as selected.
+absent_modules=
 check_external_modules() {
 	local word=$1 flavour=$2 MODINSTALLED LOSTMODS num
 	[ -n "$flavour" ] || return
@@ -423,12 +424,16 @@ check_external_modules() {
 		echo >&2 "${RED}installed for your $word $flavour kernel:${NORM}"
 		# shellcheck disable=SC2086
 		echo >&2 "  " $LOSTMODS
+		absent_modules=1
 	fi
 }
 
 check_external_modules "previous" "$kernel_flavour"
 [ "$current_kernel_flavour" != "$kernel_flavour" ] && \
 check_external_modules "BOOTED" "$current_kernel_flavour"
+if [ -n "$absent_modules" ]; then
+	echo >&2 "${RED}Do not answer yes if these modules are important for your system.${NORM}"
+fi
 
 # user module selection interface
 user_selected_modules=