RFR: JDK-8292586: simplify cleanups in NTLMAuthSequence getCredentialsHandle [v2]

[Matthias Baesken]

> NTLMAuthSequence getCredentialsHandle has a number of cleanup paths doing various JNU_ReleaseStringPlatformChars calls; those could be placed at one place in the function.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  check for SEC_E_OK

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Changes:
  - all: https://git.openjdk.org/jdk/pull/9914/files
  - new: https://git.openjdk.org/jdk/pull/9914/files/4b6e3e14..bed824de

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9914&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9914&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9914.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9914/head:pull/9914

PR: https://git.openjdk.org/jdk/pull/9914