Use fully-qualified path to refer to the associated type

Prevent "ambiguous associated type" if one of the variants is named `Numeric`.

Author: LukeMathWalker

enumflags_derive/src/lib.rs

@@ -345,7 +345,7 @@ fn gen_enumflags(ast: &mut DeriveInput, default: Vec<Ident>) -> Result<TokenStre
                 const BITFLAGS_TYPE_NAME : &'static str =
                     concat!("BitFlags<", stringify!(#ident), ">");
 
-                fn bits(self) -> Self::Numeric {
+                fn bits(self) -> <Self as ::enumflags2::_internal::RawBitFlags>::Numeric {
                     self as #repr
                 }
             }