rustc: Strip struct fields and enum variants

Closes #11085
Add testing tutorial to docs
Fix usage of rustc --ls on invalid files

Closes #11259
Update references to rustc.rc in README.
Bump version to 0.9
libsyntax: Make the parser mutable
libsyntax: De-`@mut` `quote_depth` in the parser
libsyntax: De-`@mut` `token` in the parser
libsyntax: De-`@mut` `Parser::span`
libsyntax: De-`@mut` `Parser::last_span`
libsyntax: De-`@mut` `Parser::last_token`
libsyntax: De-`@mut` `Parser::buffer`
libsyntax: De-`@mut` `Parser::buffer_start` and `Parser::buffer_end`
libsyntax: De-`@mut` `Parser::tokens_consumed`
libsyntax: De-`@mut` `Parser::restriction`
libsyntax: De-`@mut` `Parser::obsolete_set`
libsyntax: De-`@mut` `Parser::mod_path_stack`
libsyntax: De-`@mut` `Parser::open_braces`
libsyntax: Remove increasingly inaccurate comment
libsyntax: Long line