Attempt to fix build failure and regressions due to r290056

Add llvm:: namespace to StringRef.
Make conversion between bool and uint64_t explicit.

llvm-svn: 290058
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 493941a..6d79ea5 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -3944,8 +3944,8 @@
   for (const auto &I:Opts.OptMap) {
     AddString(I.getKey(), Record);
     auto V = I.getValue();
-    Record.push_back(V.Supported);
-    Record.push_back(V.Enabled);
+    Record.push_back(V.Supported ? 1 : 0);
+    Record.push_back(V.Enabled ? 1 : 0);
     Record.push_back(V.Avail);
     Record.push_back(V.Core);
   }