Add information to SourceInfo whether it was created from a system file.

[fruffy]

This way we can distinguish whether a particular IR object is a system object or a program object. This can be useful in optimizations (e.g., do not remove system declarations) and debugging (printing a program etc).

Ideally, this should directly be done in the parser. With the compile options the parser should already be able to distinguish system files from the program itself.

Originally posted by @fruffy in #4752 (comment)