fix: plugin_loader compilation errors across different version of glibc

[leogr]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area build

/area plugin-sdk

/area tests

What this PR does / why we need it:

This is a follow-up PR for https://github.com/falcosecurity/plugin-sdk-go/pull/80

Unfortunately, #80 worked only for glibc >= 2.38. This PR always uses the same strlcpy internal implementation, so it works in any case.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Since we don't use cmake here, we can't just decide a built time which declaration to use (as we do in libs)

Does this PR introduce a user-facing change?:

fix: address `strlcpy` declaration error at compile time

[leogr]

/kind bug

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jasondellaluce, leogr

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/falcosecurity/plugin-sdk-go/blob/main/OWNERS)~~ [jasondellaluce,leogr] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment