SourceMgr: Use has_colors() instead of just is_displayed() before trying to use
color.

llvm-svn: 160559
diff --git a/llvm/lib/Support/SourceMgr.cpp b/llvm/lib/Support/SourceMgr.cpp
index 37a9d8f..e4e01be 100644
--- a/llvm/lib/Support/SourceMgr.cpp
+++ b/llvm/lib/Support/SourceMgr.cpp
@@ -243,8 +243,8 @@
 
 void SMDiagnostic::print(const char *ProgName, raw_ostream &S,
                          bool ShowColors) const {
-  // Display colors only if OS goes to a tty.
-  ShowColors &= S.is_displayed();
+  // Display colors only if OS supports colors.
+  ShowColors &= S.has_colors();
 
   if (ShowColors)
     S.changeColor(raw_ostream::SAVEDCOLOR, true);