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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@248005 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Driver/Driver.cpp

@@ -413,6 +413,7 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
     // 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();
   }