Core/File: Add SetSize method (currently missing Posix implementation!)

Former-commit-id: c9ffb545485d90940d620e94fd25a7256d62ab58

src/Nazara/Core/Win32/FileImpl.hpp

@@ -32,6 +32,7 @@ namespace Nz
 			bool Open(const String& filePath, UInt32 mode);
 			std::size_t Read(void* buffer, std::size_t size);
 			bool SetCursorPos(CursorPosition pos, Int64 offset);
+			bool SetSize(UInt64 size);
 			std::size_t Write(const void* buffer, std::size_t size);
 
 			FileImpl& operator=(const FileImpl&) = delete;