Synch libuv submodule to joyent/libuv, tag 0.11.14

[lucab]

As part of the ongoing effort to reduce rust-specific patches and thanks (a lot!) to @alexcrichton, we have now reached the point where we can use vanilla libuv.
As such, I'd like to propose several changes to current submodule tracking:

• drop @alexcrichton submodule and directly synch to @joyent one
• synch to tag 0.11.14, which is the first one incorporating all our patches
• keep this synch-to-tag process for future releases, starting from rust 0.9, and explicitely document the libuv version in use at each release
• forbid local-submodule changes to avoid diverging again

However, let's remind that we jumped on the 0.11.x branch but its API is not yet stable, so breakage may still occur before reaching 0.12.x.

This is prerequisite to #5563, which I'll probably tackle after this (proposed) synch.

[alexcrichton]

I'm currently waiting on one pull request to go through with libuv (979 on their end), and then after that I was planning on syncing directly to joyent/libuv instead of my fork. It would be awesome to use an external libuv! Detecting a version (b/c we have a minimum requirement) may get interesting, but it's great that we're at least in this position!

[lucab]

I didn't see your PR, I'll probably wait for the next libuv tag then.

For version detection, I'm currently shipping a pkg-config file for libuv in Debian which I'm going to push upstream soon. This can be used at least for unix, not sure about win and mac.

[alexcrichton]

my pull request in libuv has landed, I'd ideally like to wait for #10321 to land before tackling this, but it may take awhile.

[alexcrichton]

I was going to close this, but it turns out that we still need alexcrichton/libuv@7ac7e02 or otherwise we'll just infinite loop during the build process.

The corresponding libuv issue is joyent/libuv#909. Until that gets fixed in master, it looks like we won't be able to use libuv master.

[alexcrichton]

Closing, we're on libuv 0.11.25 except for one small patch to fix the build on android, so this is basically done.