Bump libuv and specify minimum Wine for xcompile

Fixes cross-compilation

- jl_stat is broken on Wine since libuv now uses NtQueryVolumeInfo
(https://github.com/joyent/libuv/commit/315d7001
and
https://github.com/joyent/libuv/commit/20a8e58a),
which is not implemented for `FileFsVolumeInformation`

```
fixme:ntdll:NtFlushInstructionCache 0xffffffffffffffff 0x1180000 524288
fixme:ntdll:NtQueryVolumeInformationFile 0xb0: volume info not supported
could not open file boot.jlwine: Unhandled page fault on read access to
0x00000008 at address 0x6e6d2617 (thread 049e), starting debugger...
```

See: https://github.com/JuliaLang/libuv/commit/a37279a1

- due to libuv changes, cross-compile must use a very recent wine.
  both uses of `getsockopt` in `libuv/win/winsock.c:uv_winsock_init` return `SOCKET_ERROR`
  on wine1.4 (which is still the default through Ubuntu 13.10).

  - Upgrading to wine1.7 from the [PPA](http://www.ubuntuupdates.org/ppa/wine) fixes the problem.

  (this `getsockopt` check never actually worked, the check
  [was previously disabled](https://github.com/joyent/libuv/commit/d170c915))