yq: Fix path resolution for external targets

[phlax]

Currently the yq target is unusable if called from an external build, this should resolve that

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Type of change

• Bug fix (change which fixes an issue)
• New feature or functionality (change which adds functionality)
• Style (white-space, formatting, etc...)
• Refactor (a code change that neither fixes a bug or adds a new feature)
• Performance (a code change that improves performance)
• Documentation (updates to documentation or READMEs)
• Chore (any other change that doesn't affect source or test files, such as configuration)

For changes visible to end-users

• Breaking change (this change will force users to change their own code or config)
• Relevant documentation has been updated
• Suggested release notes are provided below:

Test plan

• Covered by existing test cases
• New test cases added
• Manual testing; please provide instructions so we can reproduce:

[CLAassistant]

All committers have signed the CLA.

[alexeagle]

It might be a good idea to file an issue for this first, in case others want to contribute a fix for it.

[phlax]

It might be a good idea to file an issue for this first, in case others want to contribute a fix for it.

i proposed a fix as this is blocking us from being able to do some external builds - so was hoping for a quick turnaround and needed something in the interim that works

#548