Fix VC++ compilation errors


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18953 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/System/Path.cpp b/lib/System/Path.cpp
index 1c2b00e..dd0f275 100644
--- a/lib/System/Path.cpp
+++ b/lib/System/Path.cpp
@@ -26,8 +26,10 @@
 Path
 Path::GetLLVMConfigDir() {
   Path result;
+#ifdef LLVM_ETCDIR
   if (result.setDirectory(LLVM_ETCDIR))
     return result;
+#endif
   return GetLLVMDefaultConfigDir();
 }