Update the zsh completion file for rustc.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
un-xfail test for #8498 and replace prints w/ asserts
impl Clone for CString

Clone tests
impl Eq for CString
auto merge of #11840 : cmr/rust/cstr, r=kballard
auto merge of #11959 : omasanori/rust/update-zsh, r=brson

Updating the list of options and sorting it.
auto merge of #11975 : jfager/rust/r8498, r=alexcrichton

Closes #8498
Move doc/ to src/doc/

We generate documentation into the doc/ directory, so we shouldn't be
intermingling source files with generated files
Remove VPATH usage in Makefiles

This is just messing up all the doc dependencies because of such similar
directory names and file names.

Closes #11422
Rewrite the doc makefile for doc => src/doc

This continues to generate all documentation into doc, but it now looks for
source files in src/doc

Closes #11860
Closes #11970