ctest: add foreign static test

[mbyx]

Description

Adds support for testing extern statics.

Also adds support for parsing any dimensional array in make_cdecl, and makes it easier to extract ffi safe types from Option.

Sources

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI