clang-cl: Use 'pc' for the vendor field in the default triple

Leaving it unset can make the triple look confusing, especially
when using -m32 or -m64.

llvm-svn: 248005
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 384d027..af740fc 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -413,6 +413,7 @@
     // clang-cl targets MSVC-style Win32.
     llvm::Triple T(DefaultTargetTriple);
     T.setOS(llvm::Triple::Win32);
+    T.setVendor(llvm::Triple::PC);
     T.setEnvironment(llvm::Triple::MSVC);
     DefaultTargetTriple = T.str();
   }