RFR: 8249262: Initialize InstanceKlass::_package_entry during CDS dump time [v3]

[Calvin Cheung]

> With JDK-8244778, the `PackageEntry` of all archived classes (for the 3 built-in class loaders) are all created during CDS dump time. We can remember this in `InstanceKlass::_package_entry` during dump time to avoid the hashtable lookup at runtime in `InstanceKlass::set_package()` and `SystemDictionaryShared::get_package_entry_from_class_name()`.
> 
> Passed tiers 1 - 4 testing.
> 
> Just a very small perf improvement with HelloWorld:
> instr delta =        -9514    -0.0145%
> time  delta =       -0.272 ms -0.6916%

Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:

  rename SystemDictionaryShared::get_package_entry_from_class_name to SystemDictionaryShared::get_package_entry_from_class

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2206/files
  - new: https://git.openjdk.java.net/jdk/pull/2206/files/21f419ef..d9575864

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2206&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2206&range=01-02

  Stats: 5 lines in 2 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2206.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2206/head:pull/2206

PR: https://git.openjdk.java.net/jdk/pull/2206