Don't use \n in sed - a GNU extension, avoid it.

autogen.sh

@@ -68,7 +68,8 @@ fi
 
 # Generate po/POTFILES.in
 $XGETTEXT --keyword=_ --keyword=N_ --output=- `find . -name '*.[ch]'` | \
-	sed -ne '/^#:/{s/#://;s/:[0-9]*/\n/g;s/ //g;p;}' | \
+	sed -ne '/^#:/{s/#://;s/:[0-9]*/\
+/g;s/ //g;p;}' | \
 	grep -v '^$' | sort | uniq | grep -v 'regex.c' >po/POTFILES.in
 
 ACLOCAL_INCLUDES="-I m4"