hg: build-infra/jdk9: * Restore missing CXX_O_FLAG_DEBUG_JVM which made slowdebug JVM builds incorrect.

[magnus.ihse.bursie at oracle.com]

Changeset: 2b87135f58b3
Author:    ihse
Date:      2016-02-18 23:34 +0100
URL:       http://hg.openjdk.java.net/build-infra/jdk9/rev/2b87135f58b3

* Restore missing CXX_O_FLAG_DEBUG_JVM which made slowdebug JVM builds incorrect.
* Fix typo from merge mistake
* Restructure spec.gmk.in to minimize integration conflicts.

! common/autoconf/flags.m4
! common/autoconf/generated-configure.sh
! common/autoconf/spec.gmk.in