Enable amendments in genesis ledger (RIPD-1281)

When started with "--start", put all known, non-vetoed
amendments in the genesis ledger. This avoids the need
to wait 256 ledgers before amendments are enabled when
testing with a fresh ledger.

src/ripple/app/misc/AmendmentTable.h

@@ -85,6 +85,13 @@ public:
     virtual std::vector <uint256>
     doValidation (std::set <uint256> const& enabled) = 0;
 
+    // The set of amendments to enable in the genesis ledger
+    // This will return all known, non-vetoed amendments.
+    // If we ever have two amendments that should not both be
+    // enabled at the same time, we should ensure one is vetoed.
+    virtual std::vector <uint256>
+    getDesired () = 0;
+
     // The two function below adapt the API callers expect to the
     // internal amendment table API. This allows the amendment
     // table implementation to be independent of the ledger

src/ripple/app/misc/impl/AmendmentTable.cpp

@@ -199,6 +199,9 @@ public:
     std::vector <uint256>
     doValidation (std::set<uint256> const& enabledAmendments) override;
 
+    std::vector <uint256>
+    getDesired () override;
+
     std::map <uint256, std::uint32_t>
     doVoting (
         NetClock::time_point closeTime,
@@ -396,6 +399,31 @@ AmendmentTableImpl::doValidation (
     return amendments;
 }
 
+std::vector <uint256>
+AmendmentTableImpl::getDesired ()
+{
+    // Get the list of amendments we support and do not
+    // veto
+    std::vector <uint256> amendments;
+    amendments.reserve (amendmentMap_.size());
+
+    {
+        std::lock_guard <std::mutex> sl (mutex_);
+        for (auto const& e : amendmentMap_)
+        {
+            if (e.second.supported && ! e.second.vetoed)
+            {
+                amendments.push_back (e.first);
+            }
+        }
+    }
+
+    if (!amendments.empty())
+        std::sort (amendments.begin (), amendments.end ());
+
+    return amendments;
+}
+
 std::map <uint256, std::uint32_t>
 AmendmentTableImpl::doVoting (
     NetClock::time_point closeTime,