Add support for passing '-target armv8' through the Driver.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184970 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index b058733..47a5f33 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -112,6 +112,7 @@
     .Cases("armv7k", "armv7-k", "armv7k")
     .Cases("armv7m", "armv7-m", "armv7m")
     .Cases("armv7s", "armv7-s", "armv7s")
+    .Cases("armv8", "armv8a", "armv8-a", "armv8")
     .Default(0);
 }