8229485: Add decrementExact(), incrementExact(), and negateExact() to java.lang.StrictMath
Summary: three methods are added to StrictMath for consistency with Math. Tests are updated accordingly.
Reviewed-by: bpb, lancea, igerasim, dfuchs, joehw, rriggs
Contributed-by: Julia Boes <julia.boes@oracle.com>