Fix pr13749. There is still a lot of code using getArchName that should be
using getArch, but I will try to fix them one at time to add tests.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164460 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index 2517b30..d7eaed1 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -1416,7 +1416,7 @@
 bool Generic_GCC::IsUnwindTablesDefault() const {
   // FIXME: Gross; we should probably have some separate target
   // definition, possibly even reusing the one in clang.
-  return getArchName() == "x86_64";
+  return getArch() == llvm::Triple::x86_64;
 }
 
 const char *Generic_GCC::GetDefaultRelocationModel() const {