Add missing override keyword:

* Enable the `suggest-override` warning for gcc
* Fix all functions that were flagged by that warning

src/test/app/AmendmentTable_test.cpp

@@ -757,7 +757,7 @@ public:
         BEAST_EXPECT(table->hasUnsupportedEnabled());
     }
 
-    void run ()
+    void run () override
     {
         testConstruct();
         testGet ();

src/test/app/Check_test.cpp

@@ -1817,7 +1817,7 @@ class Check_test : public beast::unit_test::suite
     }
 
 public:
-    void run ()
+    void run () override
     {
         testEnabled();
         testCreateValid();

src/test/app/CrossingLimits_test.cpp

@@ -257,7 +257,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         auto testAll = [this](FeatureBitset features) {
             testStepLimit(features);

src/test/app/DeliverMin_test.cpp

@@ -108,7 +108,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         using namespace jtx;
         auto const sa = supported_amendments();

src/test/app/Discrepancy_test.cpp

@@ -141,7 +141,7 @@ class Discrepancy_test : public beast::unit_test::suite
     }
 
 public:
-    void run ()
+    void run () override
     {
         using namespace test::jtx;
         auto const sa = supported_amendments();

src/test/app/Freeze_test.cpp

@@ -521,7 +521,7 @@ class Freeze_test : public beast::unit_test::suite
 
 public:
 
-    void run()
+    void run() override
     {
         auto testAll = [this](FeatureBitset features)
         {

src/test/app/HashRouter_test.cpp

@@ -284,7 +284,7 @@ class HashRouter_test : public beast::unit_test::suite
 public:
 
     void
-    run()
+    run() override
     {
         testNonExpiration();
         testExpiration();

src/test/app/LedgerHistory_test.cpp

@@ -239,7 +239,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         testHandleMismatch();
     }

src/test/app/LedgerLoad_test.cpp

@@ -217,7 +217,7 @@ class LedgerLoad_test : public beast::unit_test::suite
     }
 
 public:
-    void run ()
+    void run () override
     {
         beast::temp_dir td;
         auto sd = setupLedger(td);

src/test/app/LoadFeeTrack_test.cpp

@@ -27,7 +27,7 @@ namespace ripple {
 class LoadFeeTrack_test : public beast::unit_test::suite
 {
 public:
-    void run ()
+    void run () override
     {
         Config d; // get a default configuration object
         LoadFeeTrack l;

src/test/app/OfferStream_test.cpp

@@ -32,7 +32,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         test();
     }

src/test/app/OversizeMeta_test.cpp

@@ -115,7 +115,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         test();
     }
@@ -181,7 +181,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         auto const result = bfind(100, 9000,
             [&](std::size_t n) { return oversize(n); });

src/test/app/Path_test.cpp

@@ -1352,7 +1352,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         source_currencies_limit();
         no_direct_path_no_intermediary_no_alternatives();

src/test/app/SHAMapStore_test.cpp

@@ -623,7 +623,7 @@ public:
         lastRotated = ledgerSeq - 1;
     }
 
-    void run()
+    void run() override
     {
         testClear();
         testAutomatic();

src/test/app/SetRegularKey_test.cpp

@@ -92,7 +92,7 @@ public:
         env(jv, ter(temINVALID_FLAG));
     }
 
-    void run()
+    void run() override
     {
         testDisableMasterKey();
         testPasswordSpent();

src/test/app/SetTrust_test.cpp

@@ -204,7 +204,7 @@ public:
 
     }
 
-    void run()
+    void run() override
     {
         testFreeTrustlines(true, false);
         testFreeTrustlines(false, true);

src/test/app/Taker_test.cpp

@@ -63,7 +63,7 @@ class Taker_test : public beast::unit_test::suite
         }
 
         STAmount
-        get_funds (AccountID const& owner, STAmount const& funds) const
+        get_funds (AccountID const& owner, STAmount const& funds) const override
         {
             if (owner == account ())
                 return funds_;
@@ -358,7 +358,7 @@ public:
     }
 
     void
-    run()
+    run() override
     {
         test_xrp_to_iou ();
         test_iou_to_xrp ();

src/test/app/Ticket_test.cpp

@@ -379,7 +379,7 @@ class Ticket_test : public beast::unit_test::suite
     }
 
 public:
-    void run ()
+    void run () override
     {
         testTicketNotEnabled ();
         testTicketCancelNonexistent ();

src/test/app/TrustAndBalance_test.cpp

@@ -487,7 +487,7 @@ class TrustAndBalance_test : public beast::unit_test::suite
     }
 
 public:
-    void run ()
+    void run () override
     {
         testTrustNonexistent ();
         testCreditLimit ();

src/test/app/TxQ_test.cpp

@@ -2774,7 +2774,7 @@ public:
         }
     }
 
-    void run()
+    void run() override
     {
         testQueue();
         testLocalTxRetry();