Update api/current.txt for setuid deprecation

android.system.Os.setuid, setgid, seteuid and setegid never meant to be
public APIs for apps.  As suggested by API council, the plan is to
deprecate in Q, and move to SystemApi in R if needed.

Test: build
Bug: 77707533
Change-Id: I87b2eb7823109200d9073db01d709ef50a4622de