Remove patch for compatibility with old gcc

contrib/libs/cxxsupp/libcxx/include/__bit/bit_cast.h

@@ -11,7 +11,6 @@
 #define _LIBCPP___BIT_BIT_CAST_H
 
 #include <__config>
-#include <cstring>
 #include <type_traits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -29,19 +28,6 @@ template <class _ToType, class _FromType>
 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr _ToType bit_cast(const _FromType& __from) noexcept {
   return __builtin_bit_cast(_ToType, __from);
 }
-#else _LIBCPP_STD_VER > 14
-
-template<class _ToType, class _FromType, class = enable_if_t<
-  sizeof(_ToType) == sizeof(_FromType) &&
-  is_trivially_copyable<_ToType>::value &&
-  is_trivially_copyable<_FromType>::value
->>
-_LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI
-constexpr _ToType bit_cast(_FromType const& __from) noexcept {
-    _ToType __to;
-    ::memcpy(&__to, &__from, sizeof(__from));
-    return __to;
-}
 
 #endif // _LIBCPP_STD_VER > 17