RFR: 8285838: DST not applying properly with zone id offset set with TZ env variable [v2]

[Gaurav Chaudhari]

> This fix ensures that when a lookup for a custom TZ code fails, and an attempt is made to find the GMT offset in order to get the current time, Daylight savings rules are applied correctly.

Gaurav Chaudhari has updated the pull request incrementally with one additional commit since the last revision:

  8285838: Revised changes for Custom TZ DST test fixes.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8661/files
  - new: https://git.openjdk.java.net/jdk/pull/8661/files/dcf762a5..41e75494

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8661&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8661&range=00-01

  Stats: 94 lines in 3 files changed: 20 ins; 62 del; 12 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8661.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8661/head:pull/8661

PR: https://git.openjdk.java.net/jdk/pull/8661