Remove terrible awful no-good evil hack

The breakage is being addressed in rust itself.

src/function.rs

@@ -122,7 +122,6 @@ impl<'lua> Function<'lua> {
     /// # }
     /// ```
     pub fn bind<A: ToLuaMulti<'lua>>(&self, args: A) -> Result<Function<'lua>> {
-        #[cfg_attr(unwind, unwind)]
         unsafe extern "C" fn bind_call_impl(state: *mut ffi::lua_State) -> c_int {
             let nargs = ffi::lua_gettop(state);
             let nbinds = ffi::lua_tointeger(state, ffi::lua_upvalueindex(2)) as c_int;

src/lib.rs

@@ -1,5 +1,3 @@
-#![cfg_attr(unwind, feature(unwind_attributes))]
-
 //! # High-level bindings to Lua
 //!
 //! The `rlua` crate provides safe high-level bindings to the [Lua programming language].

src/lua.rs

@@ -759,7 +759,6 @@ impl Lua {
     pub(crate) unsafe fn userdata_metatable<T: UserData>(&self) -> Result<c_int> {
         // Used if both an __index metamethod is set and regular methods, checks methods table
         // first, then __index metamethod.
-        #[cfg_attr(unwind, unwind)]
         unsafe extern "C" fn meta_index_impl(state: *mut ffi::lua_State) -> c_int {
             ffi::luaL_checkstack(state, 2, ptr::null());
 
@@ -997,7 +996,6 @@ impl Lua {
         &'lua self,
         func: Callback<'callback, 'static>,
     ) -> Result<Function<'lua>> {
-        #[cfg_attr(unwind, unwind)]
         unsafe extern "C" fn callback_call_impl(state: *mut ffi::lua_State) -> c_int {
             callback_error(state, || {
                 let lua = Lua {

src/util.rs

@@ -119,7 +119,6 @@ where
         nresults: c_int,
     }
 
-    #[cfg_attr(unwind, unwind)]
     unsafe extern "C" fn do_call<F, R>(state: *mut ffi::lua_State) -> c_int
     where
         F: FnOnce(*mut ffi::lua_State) -> R,
@@ -270,7 +269,6 @@ pub unsafe fn take_userdata<T>(state: *mut ffi::lua_State) -> T {
     ptr::read(ud)
 }
 
-#[cfg_attr(unwind, unwind)]
 pub unsafe extern "C" fn userdata_destructor<T>(state: *mut ffi::lua_State) -> c_int {
     callback_error(state, || {
         take_userdata::<T>(state);
@@ -308,7 +306,6 @@ where
 // Takes an error at the top of the stack, and if it is a WrappedError, converts it to an
 // Error::CallbackError with a traceback, if it is some lua type, prints the error along with a
 // traceback, and if it is a WrappedPanic, does not modify it.
-#[cfg_attr(unwind, unwind)]
 pub unsafe extern "C" fn error_traceback(state: *mut ffi::lua_State) -> c_int {
     // I believe luaL_traceback requires this much free stack to not error.
     const LUA_TRACEBACK_STACK: c_int = 11;
@@ -355,7 +352,6 @@ pub unsafe extern "C" fn error_traceback(state: *mut ffi::lua_State) -> c_int {
 }
 
 // A variant of pcall that does not allow lua to catch panic errors from callback_error
-#[cfg_attr(unwind, unwind)]
 pub unsafe extern "C" fn safe_pcall(state: *mut ffi::lua_State) -> c_int {
     ffi::luaL_checkstack(state, 2, ptr::null());
 
@@ -378,9 +374,7 @@ pub unsafe extern "C" fn safe_pcall(state: *mut ffi::lua_State) -> c_int {
 }
 
 // A variant of xpcall that does not allow lua to catch panic errors from callback_error
-#[cfg_attr(unwind, unwind)]
 pub unsafe extern "C" fn safe_xpcall(state: *mut ffi::lua_State) -> c_int {
-    #[cfg_attr(unwind, unwind)]
     unsafe extern "C" fn xpcall_msgh(state: *mut ffi::lua_State) -> c_int {
         ffi::luaL_checkstack(state, 2, ptr::null());
 
@@ -480,7 +474,6 @@ pub unsafe fn init_error_metatables(state: *mut ffi::lua_State) {
 
     // Create error metatable
 
-    #[cfg_attr(unwind, unwind)]
     unsafe extern "C" fn error_tostring(state: *mut ffi::lua_State) -> c_int {
         ffi::luaL_checkstack(state, 2, ptr::null());
 
@@ -544,7 +537,6 @@ pub unsafe fn init_error_metatables(state: *mut ffi::lua_State) {
 
     // Create destructed userdata metatable
 
-    #[cfg_attr(unwind, unwind)]
     unsafe extern "C" fn destructed_error(state: *mut ffi::lua_State) -> c_int {
         ffi::luaL_checkstack(state, 2, ptr::null());
         push_wrapped_error(state, Error::CallbackDestructed);