Fix VC++ compilation errors

llvm-svn: 18953
diff --git a/llvm/lib/System/Path.cpp b/llvm/lib/System/Path.cpp
index 1c2b00e6..dd0f275 100644
--- a/llvm/lib/System/Path.cpp
+++ b/llvm/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();
 }