fix: cbindgen extern fnc (#58)

livekit-ffi/cbindgen.toml

@@ -1,4 +1,4 @@
-language = "C"
+language = "C++"
 include_guard = "livekit_ffi"
 autogen_warning = "/* Warning, this file is autogenerated. Don't modify this manually. */"
 usize_is_size_t = true

livekit-ffi/include/livekit_ffi.h

@@ -3,15 +3,18 @@
 
 /* Warning, this file is autogenerated. Don't modify this manually. */
 
-#include <stdarg.h>
-#include <stdbool.h>
-#include <stddef.h>
-#include <stdint.h>
-#include <stdlib.h>
+#include <cstdarg>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <ostream>
+#include <new>
 
-typedef size_t FfiHandleId;
+using FfiHandleId = size_t;
 
-#define INVALID_HANDLE 0
+constexpr static const FfiHandleId INVALID_HANDLE = 0;
+
+extern "C" {
 
 FfiHandleId livekit_ffi_request(const uint8_t *data,
                                 size_t len,
@@ -20,4 +23,6 @@ FfiHandleId livekit_ffi_request(const uint8_t *data,
 
 bool livekit_ffi_drop_handle(FfiHandleId handle_id);
 
-#endif /* livekit_ffi */
+} // extern "C"
+
+#endif // livekit_ffi