Add definitions for AMD's bobcat (aka btver1)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147846 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Host.cpp b/lib/Support/Host.cpp
index 86d1c5d..3f3cdca 100644
--- a/lib/Support/Host.cpp
+++ b/lib/Support/Host.cpp
@@ -298,6 +298,8 @@
         }
       case 16:
         return "amdfam10";
+      case 20:
+        return "btver1";
       case 21:
         return "bdver1";
     default: