wstring to Fstring, works on windows, fails on Android

This works well on windows and prints the unicode code text fine,

std::wstring  s = L"Unicode text"
GEngine->AddOnScreenDebugMessage (-1, 15, FColor::White, s.c_str ());

but when building on Android NDK, wstring does not conversion

Engine.h(1792,7): note: candidate function not viable: no known conversion from 'const std::__ndk1::basic_string<wchar_t, std::__ndk1::char_traits<wchar_t>, std::__ndk1::allocator<wchar_t> >::value_type *' (aka 'const wchar_t *')