Multiwindow example panics when debug feature is enabled

[SergeevPavel]

I try cargo run --bin multiwindow --features=debug and get

thread 'main' panicked at 'assertion failed: profiler.borrow().is_none()', /Users/pavel/.cargo/registry/src/github.com-1ecc6299db9ec823/thread_profiler-0.1.3/src/lib.rs:95:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
fish: 'cargo run --bin multiwindow --f…' terminated by signal SIGABRT (Abort)

As far as I understand the problem is in double initializaition of thread_profiler for compositor thread. What do you think about moving it under wr_has_been_initialized condition?

SergeevPavel@7a2587a

[kvark]

Looks reasonable to me!