RFR: 8271008: appcds/*/MethodHandlesAsCollectorTest.java tests time out because of excessive GC (CodeCache GC Threshold) in loom

[Coleen Phillimore]

In Loom there's a full heap walk when the sweeper is triggered.  Many of the triggers in this test case are for the adapters created by the test, which are not deallocated.  Since there is a fall back to other code cache heap areas for NonNMethod and for NMethodProfiled, made the function CodeCache::reverse_free_ratio() examine the total code cache available rather than the specific area that it is allocating into.  The compilation policy also uses this to increase the C1 compile threshold so also uses the entire free code cache size to calculate new threshold (ask @TobiHartmann about this).  Thanks to Tobias for the discussion for this fix.
Tested with tier1-4.

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Commit messages:
 - 8271008: appcds/*/MethodHandlesAsCollectorTest.java tests time out because of excessive GC (CodeCache GC Threshold) in loom

Changes: https://git.openjdk.java.net/jdk/pull/7514/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7514&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271008
  Stats: 36 lines in 5 files changed: 6 ins; 10 del; 20 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7514.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7514/head:pull/7514

PR: https://git.openjdk.java.net/jdk/pull/7514