Update rustdoc testing to test all code blocks

It's too easy to forget the `rust` tag to have a code example tested, and it's
far more common to have testable code than untestable code.

This alters rustdoc to have only two directives, `ignore` and `should_fail`. The
`ignore` directive ignores the code block entirely, and the `should_fail`
directive has been fixed to only fail the test if the code execution fails, not
also compilation.

0 files changed, 0 insertions, 0 deletions