RFR: 8319165: hsdis binutils: warns on empty string as option string

[Robbin Ehn]

Hi, please consider.

insn_options[0] is set to empty string if there is no options (NULL or empty strings).
Checking it for empty string should cover both cases, caller option is NULL or caller option is empty string.

Tested hsdis no longer gives me the warning.

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Commit messages:
 - Check for empty string instead

Changes: https://git.openjdk.org/jdk/pull/16433/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16433&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319165
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/16433.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16433/head:pull/16433

PR: https://git.openjdk.org/jdk/pull/16433