hg: jdk/sandbox: 8241374: add Math.absExact

[chris.hegarty at oracle.com]

Changeset: 04b9012767e2
Author:    darcy
Date:      2020-03-30 13:49 -0700
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/04b9012767e2

8241374: add Math.absExact
Reviewed-by: smarks, chegar, bpb

! src/java.base/share/classes/java/lang/Math.java
! src/java.base/share/classes/java/lang/StrictMath.java
+ test/jdk/java/lang/Math/AbsTests.java