Deprecate customize_airootfs.sh

Show a deprecation notice if airootfs/root/customize_airootfs.sh is found.

configs/releng/airootfs/root/customize_airootfs.sh

@@ -2,6 +2,8 @@
 
 set -e -u
 
+echo 'Warning: customize_airootfs.sh is deprecated! Support for it will be removed in a future archiso version.'
+
 sed -i 's/#\(en_US\.UTF-8\)/\1/' /etc/locale.gen
 locale-gen
 

configs/releng/build.sh

@@ -117,6 +117,7 @@ make_setup_mkinitcpio() {
 
 # Customize installation (airootfs)
 make_customize_airootfs() {
+    if [[ -e "${work_dir}/x86_64/airootfs/root/customize_airootfs.sh" ]]; then
         if [ -n "${verbose}" ]; then
             mkarchiso -v -w "${work_dir}/x86_64" -C "${work_dir}/pacman.conf" -D "${install_dir}" \
                 -r '/root/customize_airootfs.sh' run
@@ -125,6 +126,7 @@ make_customize_airootfs() {
                 -r '/root/customize_airootfs.sh' run
         fi
         rm "${work_dir}/x86_64/airootfs/root/customize_airootfs.sh"
+    fi
 }
 
 # Prepare kernel/initramfs ${install_dir}/boot/