transpile: add cases for macOS header typedefs

Author: fw-immunant

c2rust-transpile/src/c_ast/conversion.rs

@@ -1980,6 +1980,11 @@ impl ConversionContext {
                             "__int32_t" => CTypeKind::Int32,
                             "__int64_t" => CTypeKind::Int64,
                             "__int128_t" => CTypeKind::Int128,
+                            // on darwin, stdint.h typedefs uintN_t from u_intN_t:
+                            "u_int8_t" => CTypeKind::UInt8,
+                            "u_int16_t" => CTypeKind::UInt16,
+                            "u_int32_t" => CTypeKind::UInt32,
+                            "u_int64_t" => CTypeKind::UInt64,
                             _ => {
                                 eprintln!("Unknown fixed-size type typedef {name}!");
                                 return None;