Switch all of the "isysroot" const char*'s throughout the AST reader
and writer to StringRef or std::string, as appropriate.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@135769 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ChainedIncludesSource.cpp b/lib/Serialization/ChainedIncludesSource.cpp
index 8337c70..a356dd6 100644
--- a/lib/Serialization/ChainedIncludesSource.cpp
+++ b/lib/Serialization/ChainedIncludesSource.cpp
@@ -32,7 +32,7 @@
                              ASTDeserializationListener *deserialListener = 0) {
   Preprocessor &PP = CI.getPreprocessor();
   llvm::OwningPtr<ASTReader> Reader;
-  Reader.reset(new ASTReader(PP, &CI.getASTContext(), /*isysroot=*/0,
+  Reader.reset(new ASTReader(PP, &CI.getASTContext(), /*isysroot=*/"",
                              /*DisableValidation=*/true));
   Reader->setASTMemoryBuffers(memBufs, numBufs);
   Reader->setDeserializationListener(deserialListener);
@@ -103,7 +103,7 @@
     llvm::OwningPtr<ASTConsumer> consumer;
     consumer.reset(new PCHGenerator(Clang->getPreprocessor(), "-",
                                     /*Chaining=*/!firstInclude,
-                                    /*isysroot=*/0, &OS));
+                                    /*isysroot=*/"", &OS));
     Clang->getASTContext().setASTMutationListener(
                                             consumer->GetASTMutationListener());
     Clang->setASTConsumer(consumer.take());