RFR: 8267556: Enhance class paths check during runtime

[Calvin Cheung]

On Wed, 9 Jun 2021 20:53:43 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> During CDS dump time, if an entry in the classpath isn't a jar file, the entry will not be recorded in the archive header. However, during runtime, it attempts to compare all the entries in the classpath against the entries from the archive header. The loading of CDS archive would fail if there exists an non-jar entry in the classpath.
>> 
>> The proposed patch addresses the above issue. It adds a `bool _has_non_jar_in_classpath` to indicate if a non-jar entry has been encountered during dump time in the archive header. This is to minimize the performance impact for the usual cases where there is no non-jar entry in the classpath.
>> 
>> - [x] mach5 tiers 1 - 4 (including the new test)
>> 
>> This is targeted for JDK18.
>
> LGTM

@iklam, @yminqi Thanks for the review!

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PR: https://git.openjdk.java.net/jdk/pull/4402