Compatibility_matrix: s/current/4/

To indicate frozen state/development shouldn't occur here.

Bug: 126892442
Test: TH (build checks compatibility matrices)
Change-Id: I3daf93d750462bf7dcb698a353801bc55a459d45
(cherry picked from commit 86eb7fc62bd138c746e20171124abaf9b975006c)
Merged-In: I3daf93d750462bf7dcb698a353801bc55a459d45
3 files changed