Remove the branch merging optimisations for slice patterns

They were only correct in the simplest case. Some of the optimisations
are certainly possible but should be introduced carefully and only
when the whole pattern codegen infrastructure is in a better shape.

Fixes #16648.
Make doc search results use <a> tags instead of js for navigating

This has the primary advantage of not interfering with browser default
behavior for links like being able to cmd/ctrl+click on a result to open
the result in a new tab but leave the current page as-is (previous
behavior both opened a new tab and changed the current tab's location to
the result's)
Updated to new extern crate syntax.
Added warning for old deprecated syntax
Fix ICE when casting `&[T]` to `*const [T]`

Closes #16947
Handle custom deref returning fat pointers

Closes #16930
bitv: add larger tests, better benchmarks & remove dead code.

There were no tests for iteration etc. with more than 5 elements,
i.e. not even going beyond a single word. This situation is rectified.

Also, the only benchmarks for `set` were with a constant bit value,
which was not indicative of every situation, due to inlining & branch
removal. This adds a benchmark at the other end of the spectrum: random
input.
libnative/io/file_unix: remove superfluous retry().

These syscalls don't return EINTR:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstat.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/mkdir.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/unlink.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/rename.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/rmdir.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/symlink.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/link.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstatat.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/utime.html
libtime: Fix adding negative duration to Timespec.
auto merge of #16953 : nick29581/rust/dst-bug-7, r=pcwalton

Closes #16947 

r?
Print file permissions in octal form.

Closes #16943.
auto merge of #16954 : nick29581/rust/dst-bug-deref, r=nikomatsakis

Closes #16930 

r?
auto merge of #16961 : huonw/rust/bitv-twiddle, r=alexcrichton

bitv: add larger tests, better benchmarks & remove dead code.

There were no tests for iteration etc. with more than 5 elements,
i.e. not even going beyond a single word. This situation is rectified.

Also, the only benchmarks for `set` were with a constant bit value,
which was not indicative of every situation, due to inlining & branch
removal. This adds a benchmark at the other end of the spectrum: random
input.
Fix some non-FFI-safe types in externs
Use a visitor to look for non-FFI-safe types

Fixes #16250.
auto merge of #16972 : ruud-v-a/rust/timespec-arithmetic, r=alexcrichton

Changing from `Timespec` to `Duration` introduced a bug for negative durations. This fixes that.
Fix spelling errors and capitalization.
auto merge of #16909 : carols10cents/rust/docs-links, r=alexcrichton

This has the primary advantage of not interfering with browser default behavior for links like being able to cmd/ctrl+click on a result to open the result in a new tab but leave the current page as-is (previous behavior both opened a new tab and changed the current tab's location to the result's).

I've done my best to keep the rest of the behavior and the appearance the same-- the whole row still highlights, still has a hand cursor, still moves to the result page with a normal click, arrows+enter still work. If the result is on the current page, the search is simply hidden.

The biggest difference in behavior is that people using tab to navigate through the links will have to hit tab twice for each row, since each cell has its own `a` tag.. I could fix this by switching to `div`s and `span`s instead of a table, but that's potentially more CSS finicky?

The biggest difference in appearance is probably that all the text in the search results is Fira Sans now, instead of just the method name with the rest of the text in Source Serif Pro. I can put this appearance back, but it looks like all links anywhere on the page are Fira Sans. Only the name was in an `a` tag before, but the whole row was ACTING like a link, so I think this is actually more consistent.

[I've pushed these changes to a gh-pages repo](https://carols10cents.github.io/rustdoc-playground/std/index.html?search=t) if you'd like to take a look at the effects; note that I also have my changes for PR #16735 there too so the search results will be sorted differently than on master.
auto merge of #16883 : jakub-/rust/issue-16648, r=pcwalton

They were only correct in the simplest case. Some of the optimisations
are certainly possible but should be introduced carefully and only
when the whole pattern codegen infrastructure is in a better shape.

Fixes #16648.
Print file permissions with 4 digits.
auto merge of #16964 : nodakai/rust/libnative-superfluous-retry, r=alexcrichton

Those syscalls listed below don't return `EINTR`, so wrapping them with `retry()` is superfluous.

But I admit the current code is better from the viewpoint of difensive programming, given that the overhead of `retry()` is really cheap...

http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstat.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/mkdir.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/unlink.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/rename.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/rmdir.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/symlink.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/link.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/fstatat.html
http://pubs.opengroup.org/onlinepubs/9699919799/functions/utime.html