Remove lifetime from the Event

Lifetimes don't work nicely when dealing with multithreaded environments
in the current design of the existing winit's event handling model, so
remove it in favor of `InnerSizeWriter` fences passed to client, so they
could try to update the size.

Fixes #1387.

src/error.rs

@@ -8,6 +8,8 @@ use crate::platform_impl;
 pub enum ExternalError {
     /// The operation is not supported by the backend.
     NotSupported(NotSupportedError),
+    /// The operation was ignored.
+    Ignored,
     /// The OS cannot perform the operation.
     Os(OsError),
 }
@@ -74,6 +76,7 @@ impl fmt::Display for ExternalError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
         match self {
             ExternalError::NotSupported(e) => e.fmt(f),
+            ExternalError::Ignored => write!(f, "Operation was ignored"),
             ExternalError::Os(e) => e.fmt(f),
         }
     }