Check if a terminal supports colors on Windows properly

Summary:
Previously we SetUseColor(true) wrongly when output was not a terminal so it broken some (not public) bots.

Thanks for issue report, @stella.stamenova

Reviewers: stella.stamenova, zturner

Reviewed By: stella.stamenova

Subscribers: abidh, lldb-commits, stella.stamenova

Differential Revision: https://reviews.llvm.org/D51772

llvm-svn: 341746

lldb/source/Core/Debugger.cpp

@@ -812,7 +812,6 @@ Debugger::Debugger(lldb::LogOutputCallback log_callback, void *baton)
   // Enabling use of ANSI color codes because LLDB is using them to highlight
   // text.
   llvm::sys::Process::UseANSIEscapeCodes(true);
-  SetUseColor(true);
 #endif
 }
 

lldb/source/Host/common/File.cpp

@@ -806,6 +806,9 @@ void File::CalculateInteractiveAndTerminal() {
     if (_isatty(fd)) {
       m_is_interactive = eLazyBoolYes;
       m_is_real_terminal = eLazyBoolYes;
+#if defined(ENABLE_VIRTUAL_TERMINAL_PROCESSING)
+      m_supports_colors = eLazyBoolYes;
+#endif
     }
 #else
     if (isatty(fd)) {