RFR: 8047734 : Back out use of -Og

[Mike Duigou]

Hello all;

This change backs out use of the optimized for debugging "-Og" in favour of the traditional "-O0". Initial evaluation seemed to indicate that "-Og" provided all the necessary debugging information but this has turned out to be incorrect. It seems that information is missing with the "-Og" optimization option combined with the default "-g" symbols option. More investigation is needed but that will be done in a future changeset.

jbsbug: https://bugs.openjdk.java.net/browse/JDK-8047734
webrev: http://cr.openjdk.java.net/~mduigou/JDK-8047734/0/webrev/

(diffs in the generated configure script are not part of this review)

The changes will be pushed through the hotspot-compiler repo.

Mike