Enable ChangeStdin/outToBinary for llvm-dis on Windows. (#4509)

This will fix issue when read input from stdin.
Without ChangeStdinToBinary, llvm-dis will get wrong size for stdin input in some case. That will cause 'Invalid bitcode size' error when parse bitcode.
MSFT_SUPPORTS_TEXTMODE_STREAMS was added a long time ago during initial file system virtualization work, the API should hit these functions under virtualized paths (and testing so far confirms this). We should keep an eye out still for a regression where the global stdin or stdout mode is unexpectedly overridden when using the API.

Author: python3kgae

lib/Support/Windows/Program.inc

@@ -470,20 +470,16 @@ ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
 #endif // HLSL Change - MSFT_SUPPORTS_CHILD_PROCESSES
 
 std::error_code sys::ChangeStdinToBinary() {
-#ifdef MSFT_SUPPORTS_TEXTMODE_STREAMS  // HLSL Change
   int result = _setmode(_fileno(stdin), _O_BINARY);
   if (result == -1)
     return std::error_code(errno, std::generic_category());
-#endif  // HLSL Change
   return std::error_code();
 }
 
 std::error_code sys::ChangeStdoutToBinary() {
-#ifdef MSFT_SUPPORTS_TEXTMODE_STREAMS  // HLSL Change
   int result = _setmode(_fileno(stdout), _O_BINARY);
   if (result == -1)
     return std::error_code(errno, std::generic_category());
-#endif  // HLSL Change
   return std::error_code();
 }