GlobalContext is not affected by panics

It has plenty of thread-safety problems, but not this one

src/context.rs

@@ -5,6 +5,8 @@ use std::ffi::CStr;
 use std::os::raw::c_void;
 use std::cell::UnsafeCell;
 use std::collections::HashMap;
+use std::panic::UnwindSafe;
+use std::panic::RefUnwindSafe;
 
 /// A special case for non-thread-aware functions.
 ///
@@ -14,6 +16,9 @@ pub struct GlobalContext {
     _not_thread_safe: UnsafeCell<YouMustUseThreadContextToShareBetweenThreads>,
 }
 
+impl UnwindSafe for GlobalContext {}
+impl RefUnwindSafe for GlobalContext {}
+
 #[doc(hidden)]
 pub trait Context {
     fn as_ptr(&self) -> ffi::Context;

src/profile.rs

@@ -530,3 +530,11 @@ fn bad_icc() {
     let err = Profile::new_icc(&[1, 2, 3]);
     assert!(err.is_err());
 }
+
+#[test]
+fn unwind_safety() {
+    let ref profile = Profile::new_xyz();
+    std::panic::catch_unwind(|| {
+        profile.clone()
+    }).unwrap();
+}