Spring cleaning: remove if-defs

[cristianoc]

The compiler codebase still has a few if-defs resolved during preprocessing.
A couple of consequences are:

• cannot turn on reformatting for some of the codebase
• cannot convert some (occasionally user-facing) files to .res
• complicates the build

CC @ryyppy

[ryyppy]

This would also include removing the .cppo files for e.g. belt, right?

[cristianoc]

Exactly right

[ryyppy]

Related #5458

[github-actions]

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