[type/__mail_aliases] Add support for Alpine Linux

Alpine's DMA package has a typo and installs "newailases" instead of
"newaliases".
I adjusted the code-remote to only run newaliases if it is available.
Otherwise, tough luck, user gotta either fix his system or run manually.

type/__mail_alias/explorer/aliases_file

@@ -28,7 +28,7 @@ check_file() {
 	fi
 }
 
-case $("$__explorer/os")
+case $("${__explorer}/os")
 in
 	(freebsd|openbsd|solaris)
 		check_file /etc/mail/aliases
@@ -36,7 +36,7 @@ in
 		# default
 		found /etc/mail/aliases
 		;;
-	(debian|devuan|ubuntu)
+	(alpine|debian|devuan|ubuntu)
 		check_file /etc/aliases
 
 		# default

type/__mail_alias/gencode-remote

@@ -142,7 +142,9 @@ if ! cmp -s "${aliases_file}" "${aliases_file}.tmp"
 then
 	# aliases file was modified, replace and run `newaliases`.
 	mv "${aliases_file}.tmp" "${aliases_file}"
-	newaliases
+
+	# run newaliases if present
+	command -v newaliases >/dev/null 2>&1 && newaliases || true
 else
 	# no modifications were made, delete the temp file.
 	rm "${aliases_file}.tmp"