Clean knowhere build warnings

[cydrain]

Issue: #1083

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cydrain

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [cydrain]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[mergify]

@cydrain 🔍 Important: PR Classification Needed!

For efficient project management and a seamless review process, it's essential to classify your PR correctly. Here's how:

1. If you're fixing a bug, label it as kind/bug.
2. For small tweaks (less than 20 lines without altering any functionality), please use kind/improvement.
3. Significant changes that don't modify existing functionalities should be tagged as kind/enhancement.
4. Adjusting APIs or changing functionality? Go with kind/feature.

For any PR outside the kind/improvement category, ensure you link to the associated issue using the format: “issue: #”.

Thanks for your efforts and contribution to the community!.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.04%. Comparing base (3c46f4c) to head (9cc2ad4).
Report is 318 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##           main    #1082       +/-   ##
=========================================
+ Coverage      0   72.04%   +72.04%     
=========================================
  Files         0       85       +85     
  Lines         0     8225     +8225     
=========================================
+ Hits          0     5926     +5926     
- Misses        0     2299     +2299     

see 85 files with indirect coverage changes

[cydrain]

/kind improvement

[cqy123456]

maybe put these util.h functions in anonymous namespace is better

[cydrain]

maybe put these util.h functions in anonymous namespace is better

@cqy123456 add namespace, please check again

[alexanderguzhva]

do I get it correct that error reporting was just disabled?

[cydrain]

Hi Alex,

I plan to enable "-Werror" to make the compiler treat all warnings as errors.
But because of issue #1081, I cannot enable this flag by now.

[cqy123456]

/lgtm