Avoid conflict with C++17 features std::byte by using uint8 type instead of byte

src/Main/GraphicUserInterface.cpp

@@ -992,7 +992,7 @@ namespace VeraCrypt
 					int showFifo = open (string (MainFrame::GetShowRequestFifoPath()).c_str(), O_WRONLY | O_NONBLOCK);
 					throw_sys_if (showFifo == -1);
 
-					byte buf[1] = { 1 };
+					uint8 buf[1] = { 1 };
 					if (write (showFifo, buf, 1) == 1)
 					{
 						close (showFifo);