[SystemZ][z/OS] Propagate IsText flag continuation

Author: abhina-sree

clang/lib/Serialization/ASTReader.cpp

@@ -5318,7 +5318,7 @@ std::string ASTReader::getOriginalSourceFile(
   // Open the AST file.
   auto Buffer = FileMgr.getBufferForFile(ASTFileName, /*IsVolatile=*/false,
                                          /*RequiresNullTerminator=*/false,
-                                         /*IsText=*/true);
+                                         /*IsText=*/false);
   if (!Buffer) {
     Diags.Report(diag::err_fe_unable_to_read_pch_file)
         << ASTFileName << Buffer.getError().message();

llvm/lib/Support/FileCollector.cpp

@@ -268,7 +268,7 @@ class FileCollectorFileSystem : public vfs::FileSystem {
   }
 
   llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
-  openFileForRead(const Twine &Path, bool IsText) override {
+  openFileForRead(const Twine &Path, bool IsText = true) override {
     auto Result = FS->openFileForRead(Path, IsText);
     if (Result && *Result)
       Collector->addFile(Path);