core: support make 4.00

Summary: Make 4.00 is now out, and builds work with it.

Test Plan: merge

Reviewers: randall.rushing, synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D606

Change-Id: I22880d3d9121232032cb7c854dfcc2d8c4ca37f3