fix: use consistent u32 type for enum constants on Windows

bindgen generates C enums as i32 by default, but on Windows MSVC this
can cause type mismatches when consuming code expects u32 constants.

Use EnumVariation::Consts to generate all enum constants as u32 for
cross-platform consistency.

Author: kajukitli

build.rs

@@ -266,6 +266,10 @@ fn generate_bindings(out_dir: &Path, include_dir: &Path) {
     .allowlist_function("nghttp2_.*")
     .allowlist_type("nghttp2_.*")
     .allowlist_var("NGHTTP2_.*")
+    // Generate enum constants as u32 for cross-platform consistency
+    // (C enums are `int` on MSVC → i32, but unsigned on GCC/Clang → u32)
+    .default_enum_style(bindgen::EnumVariation::Consts)
+    .translate_enum_integer_types(true)
     // Opaque types that should not derive Copy
     .opaque_type("nghttp2_session")
     .opaque_type("nghttp2_rcbuf")