/usr/src/linux-headers-4.15.0-1022-azure/scripts/kconfig/nconf.h is in linux-headers-4.15.0-1022-azure 4.15.0-1022.22~16.04.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/src/linux-headers-4.15.0-1022-azure/scripts/kconfig/../../../linux-azure-headers-4.15.0-1022/scripts/kconfig/nconf.h