Integrated: Fix failing jtreg tests

[William Kemper]

With these (minor) changes, generational Shenandoah passes the full suite of Shenandoah jtreg tests.

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Commit messages:
 - Fix missing include
 - Increment GC ID before starting cycle (fixes whitebox breakpoint tests)
 - Use fully qualified name for ClassFileInstaller

Changes: https://git.openjdk.java.net/shenandoah/pull/73/files
 Webrev: https://webrevs.openjdk.java.net/?repo=shenandoah&pr=73&range=00
  Stats: 24 lines in 4 files changed: 3 ins; 17 del; 4 mod
  Patch: https://git.openjdk.java.net/shenandoah/pull/73.diff
  Fetch: git fetch https://git.openjdk.java.net/shenandoah pull/73/head:pull/73

PR: https://git.openjdk.java.net/shenandoah/pull/73