Add support for the OpenBSD for Bitrig.

Patch by David Hill.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161344 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Triple.cpp b/lib/Support/Triple.cpp
index 7b26ea9..cca549d 100644
--- a/lib/Support/Triple.cpp
+++ b/lib/Support/Triple.cpp
@@ -124,6 +124,7 @@
   case RTEMS: return "rtems";
   case NativeClient: return "nacl";
   case CNK: return "cnk";
+  case Bitrig: return "bitrig";
   }
 
   llvm_unreachable("Invalid OSType");
@@ -293,6 +294,7 @@
     .StartsWith("rtems", Triple::RTEMS)
     .StartsWith("nacl", Triple::NativeClient)
     .StartsWith("cnk", Triple::CNK)
+    .StartsWith("bitrig", Triple::Bitrig)
     .Default(Triple::UnknownOS);
 }