fix(userspace/engine): fix memory leak

[therealbobo]

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

/kind release

Any specific area of the project related to this PR?

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

/area build

/area engine

/area tests

/area proposals

/area CI

What this PR does / why we need it:

This fixes a memory leak: compiler.compile() allocates a sinp_filter but never destroys it.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

fix(userspace/engine): fix memory leak

[github-actions]

This PR may bring feature or behavior changes in the Falco engine and may require the engine version to be bumped.

Please double check userspace/engine/falco_engine_version.h file. See versioning for FALCO_ENGINE_VERSION.

/hold

[therealbobo]

@incertum maybe this is related to the memory leak that you found some time ago 🤔

[incertum]

/approve

I'll gladly test deploy soon and let's see. Evidence that it also happened when using Falco only for the k8s plugins suggests this is in the right area of the code base.

At the same time tons of servers do not show any memory leaks ... This is the puzzling part. It's nothing consistent or easy to find so to say.

[poiana]

LGTM label has been added.

Git tree hash: 83d6e339143405cec91af34ac27736cec7039c6c

[FedeDP]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FedeDP, incertum, therealbobo

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[FedeDP]

/milestone 0.37.0

[FedeDP]

/unhold

[FedeDP]

/milestone 0.36.2

[FedeDP]

/milestone 0.37.0
There are conflicts; and i don't think this is that important to need custom code in the release branch.