Expunge V2 - Using new dbUtil API

Summary:
using new DbUtils Api in expunge fixer
ref : D37892943

Differential Revision: D38096685

fbshipit-source-id: 633a44691554990c5c869ac49096ff2d51aa5830

Author: Bhanu Prakash Naredla

squangle/mysql_client/Connection.h

@@ -268,7 +268,7 @@ class Connection {
   //
   // This is provided so that non-Facebook users of the HHVM extension have
   // a familiar API.
-  std::string escapeString(folly::StringPiece unescaped) {
+  std::string escapeString(folly::StringPiece unescaped) const {
     CHECK_THROW(mysql_connection_ != nullptr, db::InvalidConnectionException);
     return Query::escapeString<std::string>(
         mysql_connection_->mysql(), unescaped);