message: build: bump bitcoin_config.h packages to v0.18
  Follow-up to
diff: #define PACKAGE_NAME "Bitcoin Core"
  /* Define to the full name and version of this package. */
  -#define PACKAGE_STRING "Bitcoin Core 0.17.99"
  +#define PACKAGE_STRING "Bitcoin Core 0.18.99"
  /* Define to the one symbol short name of this package. */
  #define PACKAGE_TARNAME "bitcoin"
  #define PACKAGE_URL "https://bitcoincore.org/"
  /* Define to the version of this package. */
  -#define PACKAGE_VERSION "0.17.99"
  +#define PACKAGE_VERSION "0.18.99"
  /* Define to necessary symbol if this constant uses a non-standard name on
  your system. */
  