RFR: 8292983: ModuleReferenceImpl.computeHash should record algorithm for cache checks [v2]

[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.
> 
> Not a bug at this point, since only use SHA-256 today, but this is a landmine ready to fire. 
> 
> Additional testing:
>  - [x] Linux x86_64 release, `java/lang/module` tests

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Touchups

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/10044/files
  - new: https://git.openjdk.org/jdk/pull/10044/files/40f76f5b..03961f29

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10044&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10044&range=00-01

  Stats: 11 lines in 1 file changed: 4 ins; 2 del; 5 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