Add definitions for library functions used in cp program

[michael-schwarz]

Adds definitions for the library functions encountered during #855. The following definitions are still missing:

• atexit part of (Support for atexit, on_exit and pthread_cleanup_handlers #799)
• error
• fscanf

@sim642 Is there currently support for varargs in your library DSL? We would need it here.

[michael-schwarz]

This is against widening_global_issue by accident, but as that is likely to be merged soon, I don't think cleanup is needed.

[sim642]

Is there currently support for varargs in your library DSL? We would need it here.

Already thought of, here's a couple of examples:

analyzer/src/analyses/libraryFunctions.ml

Line 48 in 24ad290

("__builtin_prefetch", unknown (drop "addr" [] :: VarArgs (drop' [])));

analyzer/unittest/analyses/libraryDslTest.ml

Lines 21 to 27 in 24ad290

	let scanf_desc': LibraryDesc.t = LibraryDsl.(
	special ((drop "format" []) :: VarArgs (__' [w])) @@ fun (args: Cil.exp list) -> Unknown
	)
	let scanf_desc: LibraryDesc.t = LibraryDsl.(
	unknown ((drop "format" []) :: VarArgs (drop' [w]))
	)

[sim642]

I'm not sure if SV-COMP rules cover the POSIX stuff though, they're not exactly part of GCC itself, but glibc.