Remove GCC version checks

Citra can't be compiled using GCC <7 because of required C++17 support, so these version checks don't need to exist anymore.

src/common/bit_field.h

@@ -195,10 +195,8 @@ private:
 };
 #pragma pack()
 
-#if (__GNUC__ >= 5) || defined(__clang__) || defined(_MSC_VER)
 static_assert(std::is_trivially_copyable<BitField<0, 1, unsigned>>::value,
               "BitField must be trivially copyable");
-#endif
 
 template <std::size_t Position, std::size_t Bits, typename T>
 using BitFieldBE = BitField<Position, Bits, T, BETag>;