rust-bindgen: enable tests

now that we have a recent enough rustfmt

pkgs/development/tools/rust/bindgen/default.nix

@@ -29,7 +29,7 @@ rustPlatform.buildRustPackage rec {
     chmod +x $out/bin/bindgen
   '';
 
-  doCheck = false; # half the tests fail because our rustfmt is not nightly enough
+  doCheck = true;
   checkInputs =
     let fakeRustup = writeScriptBin "rustup" ''
       #!${stdenv.shell}
@@ -42,6 +42,10 @@ rustPlatform.buildRustPackage rec {
     fakeRustup # the test suite insists in calling `rustup run nightly rustfmt`
     clang
   ];
+  preCheck = ''
+    # for the ci folder, notably
+    patchShebangs .
+  '';
 
   meta = with stdenv.lib; {
     description = "C and C++ binding generator";