RFR: 8262351: Extra '0' in java.util.Formatter for '%012a' conversion with a sign character

[Ian Graves]

This fixes a zero-adding issue observed in the hex float conversion.

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Commit messages:
 - Fixing zero-padding issue in hex float conversion

Changes: https://git.openjdk.java.net/jdk/pull/2881/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2881&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262351
  Stats: 55 lines in 2 files changed: 54 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2881.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2881/head:pull/2881

PR: https://git.openjdk.java.net/jdk/pull/2881