RFR: 8357862: Java argument file is parsed unexpectedly with trailing comment

[Christian Stein]

Please review this fix to correctly parse tokens in an argument file that contains trailing comments without preceding whitespace characters before the '#' comment marker, the number sign.

The specifaction of the `java` Command has in section [java Command-Line Argument Files](https://docs.oracle.com/en/java/javase/12/docs/specs/man/java.html#java-command-line-argument-files):

Use the number sign `#` in the argument file to identify comments.
All characters following the `#` are ignored until the end of line.

There is not requirement specified to prepend a comment in a line with at least one argument with one or more preceding whitespace characters.

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Commit messages:
 - 8357862: Java argument file is parsed unexpectedly with trailing comment

Changes: https://git.openjdk.org/jdk/pull/25589/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25589&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357862
  Stats: 26 lines in 2 files changed: 23 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/25589.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25589/head:pull/25589

PR: https://git.openjdk.org/jdk/pull/25589