Replace static mutex

[ramn]

So that we can compile on stable rust

[dginev]

Btw a good idea is to start using both stable and nightly on Travis from this PR on, and possibly even beta. In the end the core idea is to make the crate work on more rust releases, rather than less.

[dginev]

And the 3 projects I am involved with that use this crate are all based on the nightly toolchain, so breaking that here would be a no-go.

[ramn]

What should I put in the travis file?

[dginev]

Based on the travis docs I'd suggest:

language: rust
rust:
  - stable
  - beta
  - nightly

[ramn]

Thanks, I'll try that. Nightly tests successfully on my machine, btw.

[ramn]

Strange, works on 1.8 nightly on macos

[dginev]

The joys of travis. I'll take a look a bit later today if you don't find an obvious cause for the travis failure.

[ramn]

Can we set RUST_BACKTRACE=1?

[dginev]

I just installed today's nightly and it broke not only your PR but also the main rust-libxml master. So not a problem for your PR, we should fix it in master first.

[dginev]

FYI it seems that xmlReadFile and htmlReadFile are now returning null pointers in the test suite.

[dginev]

@ramn I merged a fix that brings us up to date with the current nightly, would you care to rebase the PR on the latest master? I'll look into it then (Travis should pass)

[ramn]

Rebased https://github.com/jfschaefer/rust-libxml/pull/5