RFR: 8292983: ModuleReferenceImpl.computeHash ignores the algorithm for cache checks

[Aleksey Shipilev]

Look at implementation and figure out what happens if you do:


 computeHash("SHA-1") = someHash;
 computeHash("SHA-256") = ...?


The caching method should actually check the algorithms match.

Does not seem to be a problem at this point, since we seem to be only calling that methods with "SHA-256", but this is a landmine ready to fire. 

Additional testing:
 - [x] Linux x86_64 release, `java/lang/module` tests

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/10044/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10044&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292983
  Stats: 25 lines in 1 file changed: 16 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/10044.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10044/head:pull/10044

PR: https://git.openjdk.org/jdk/pull/10044