hg: jdk/submit: 8248234: Disabling UseExactTypes crashes C2

[tobias.hartmann at oracle.com]

Changeset: a707b9457c83
Author:    thartmann
Date:      2020-06-29 08:21 +0200
URL:       https://hg.openjdk.java.net/jdk/submit/rev/a707b9457c83

8248234: Disabling UseExactTypes crashes C2
Summary: Remove the flag since it is broken, untested and hasn't been used in many years.
Reviewed-by: kvn, redestad, neliasso

! src/hotspot/share/opto/c2_globals.hpp
! src/hotspot/share/opto/memnode.cpp
! src/hotspot/share/opto/type.cpp