[NFC] Renames a template parameter to avoid clashes with userspace names. (#76829)

Co-authored-by: Bogdan Graur <[email protected]>

Author: bgra8

libcxx/include/__format/format_arg_store.h

@@ -228,15 +228,15 @@ _LIBCPP_HIDE_FROM_ABI void __store_basic_format_arg(basic_format_arg<_Context>*
   ([&] { *__data++ = __format::__create_format_arg<_Context>(__args); }(), ...);
 }
 
-template <class _Context, size_t N>
+template <class _Context, size_t _Np>
 struct __packed_format_arg_store {
-  __basic_format_arg_value<_Context> __values_[N];
+  __basic_format_arg_value<_Context> __values_[_Np];
   uint64_t __types_ = 0;
 };
 
-template <class _Context, size_t N>
+template <class _Context, size_t _Np>
 struct __unpacked_format_arg_store {
-  basic_format_arg<_Context> __args_[N];
+  basic_format_arg<_Context> __args_[_Np];
 };
 
 } // namespace __format

libcxx/test/libcxx/system_reserved_names.gen.py

@@ -131,6 +131,9 @@
 #define E SYSTEM_RESERVED_NAME
 #define Ep SYSTEM_RESERVED_NAME
 #define Es SYSTEM_RESERVED_NAME
+#define N SYSTEM_RESERVED_NAME
+#define Np SYSTEM_RESERVED_NAME
+#define Ns SYSTEM_RESERVED_NAME
 #define R SYSTEM_RESERVED_NAME
 #define Rp SYSTEM_RESERVED_NAME
 #define Rs SYSTEM_RESERVED_NAME