Fix inclusion of target source file for serial API

[josesimoes]

Description

• Fix inclusion of target source file for serial API

Motivation and Context

• The build was failing for targets that have the serial stuff setup and the CMake option is OFF. The cpp file was always in the build but the header couldn't be found because the include directory was only there when the option was ON.

How Has This Been Tested?

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Signed-off-by: José Simões [email protected]

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