Don't check the isysroot path for Path::isValid(); if the user has

specified a syntactically invalid path, it's better to let the OS
diagnose the problem than to silently skip it.

llvm-svn: 120542

clang/lib/Frontend/InitHeaderSearch.cpp

@@ -110,7 +110,6 @@ void InitHeaderSearch::AddPath(const llvm::Twine &Path,
 
   // Handle isysroot.
   if (Group == System && !IgnoreSysRoot && MappedPath.isAbsolute() &&
-      IncludeSysroot.isValid() &&
       IncludeSysroot != llvm::sys::Path::GetRootDirectory()) {
     MappedPathStorage.clear();
     MappedPathStr =