Fix memory leaks in PE format

[Roeegg2]

• Fix freeing of relocation array when no relocations are present

• Reimplement canary checking for PE for speed + getting rid of memory leak when calling imports()

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the rizin book with the relevant information (if needed)

Detailed description

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Test plan

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Closing issues

All tests green
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