remove dead link to rustpkg documentation
Tweak test name and make it more specific
Add ignore-cross-compile directive for compiletest

Loadable syntax extensions don't work when cross compiling (see #12102), so the
fourcc tests all need to be ignored. They're valuable tests, so they shouldn't
be outright ignored, so they're now flagged with ignore-cross-compile
Added examples for converting vectors of u8 into strings. Also fixed some styling
Fixed fourcc example doc
auto merge of #12184 : JeremyLetang/rust/rustpkg-link, r=alexcrichton
auto merge of #12185 : nikomatsakis/rust/issue-12033-tweak-test, r=alexchrichton
auto merge of #12190 : alexcrichton/rust/fix-snap-again, r=brson

Loadable syntax extensions don't work when cross compiling (see #12102), so the
fourcc tests all need to be ignored. They're valuable tests, so they shouldn't
be outright ignored, so they're now flagged with ignore-cross-compile
auto merge of #12194 : WebeWizard/rust/master, r=cmr
Removed ty_type (previously used to represent *tydesc).
auto merge of #12180 : eddyb/rust/rm-ty_type, r=nikomatsakis
auto merge of #12196 : dguenther/rust/fix-fourcc-example, r=alexcrichton

Cleans up a few issues with `fourcc`:
* Corrects the endianness in the docs example
* Removes `#[cfg(not(test))]` (bors might not build this on Windows. If the build fails, I'll re-add it)
* Adds a FIXME referencing the LLVM assert issue we encountered with bors builds on Windows (Same error as #10872)
Refactored ast_map and friends, mainly to have Paths without storing them.