[build] Refactor/cleanup build system, easier build on ubuntu 18.04.#2947

Merged

danpovey merged 3 commits intokaldi-asr:masterfrom

danpovey:build_cleanu

Dec 31, 2018

Commits on Dec 29, 2018

[build] Some refactoring/cleanup of build system, make building easier on ubuntu 18.04.
danpovey
committed
[build] Small fix to error message in configure script
danpovey
committed

Commits on Dec 30, 2018

[build] Change default_rules.mk to hopefully eliminate travis failures.
danpovey
committed