RFR: 8277246: No need to check about KeyUsage when validating a TSA certificate [v2]

[Weijun Wang]

> There is no need to check for the KeyUsage extension when validating a TSA certificate.
> 
> A test is modified where a TSA cert has a KeyUsage but without the DigitalSignature bit.

Weijun Wang has updated the pull request incrementally with one additional commit since the last revision:

  clarify RFC requirement

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6416/files
  - new: https://git.openjdk.java.net/jdk/pull/6416/files/e7db147e..a5b3bc86

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6416&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6416&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6416.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6416/head:pull/6416

PR: https://git.openjdk.java.net/jdk/pull/6416