sim: Add a checkpoint function to test for entries

When loading a checkpoint, it's sometimes desirable to be able to test
whether an entry within a secion exists. This is currently done
automatically in the UNSERIALIZE_OPT_SCALAR macro, but it isn't
possible to do for arrays, containers, or enums. Instead of adding
even more macros, add a helper function (CheckpointIn::entryExists())
that tests for the presence of an entry.

Change-Id: I4b4646b03276b889fd3916efefff3bd552317dbc
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>

src/sim/serialize.cc

@@ -692,6 +692,12 @@ CheckpointIn::~CheckpointIn()
     delete db;
 }
 
+bool
+CheckpointIn::entryExists(const string &section, const string &entry)
+{
+    return db->entryExists(section, entry);
+}
+
 bool
 CheckpointIn::find(const string &section, const string &entry, string &value)
 {

src/sim/serialize.hh

@@ -359,6 +359,8 @@ class CheckpointIn
     bool findObj(const std::string &section, const std::string &entry,
                  SimObject *&value);
 
+
+    bool entryExists(const std::string &section, const std::string &entry);
     bool sectionExists(const std::string &section);
 
     // The following static functions have to do with checkpoint