Fix swapping of >>= and <<= in constants

This should't change behavior in practice since using these in constants
doesn't seem possible.

Closes #850

CHANGES

@@ -1,3 +1,7 @@
+# Unreleased
+
+      * Fix swapping of `>>=` and `<<=` in constants.
+
 ## 0.25.0
 
       * Re-release of yanked 0.24.6 as a major release

src/bindgen/ir/constant.rs

@@ -321,8 +321,8 @@ impl Literal {
                     syn::BinOp::BitXorEq(..) => "^=",
                     syn::BinOp::BitAndEq(..) => "&=",
                     syn::BinOp::BitOrEq(..) => "|=",
-                    syn::BinOp::ShlEq(..) => ">>=",
-                    syn::BinOp::ShrEq(..) => "<<=",
+                    syn::BinOp::ShlEq(..) => "<<=",
+                    syn::BinOp::ShrEq(..) => ">>=",
                 };
                 Ok(Literal::BinOp {
                     left: Box::new(l),