Speed up some unit tests:

A few of the slowest unit tests are modified to process a smaller data
set size, to reduce the time required to run all unit tests.

beast/chrono/tests/abstract_clock.test.cpp

@@ -88,6 +88,6 @@ public:
     }
 };
 
-BEAST_DEFINE_TESTSUITE(abstract_clock,chrono,beast);
+BEAST_DEFINE_TESTSUITE_MANUAL(abstract_clock,chrono,beast);
 
 }

beast/nudb/tests/recover_test.cpp

@@ -156,6 +156,7 @@ public:
         test_recover (lf, 0);
         test_recover (lf, 10);
         test_recover (lf, 100);
+        test_recover (lf, 1000);
     }
 };
 
@@ -168,13 +169,11 @@ public:
     run() override
     {
         float lf = 0.90f;
-        test_recover (lf, 1000);
         test_recover (lf, 10000);
+        test_recover (lf, 100000);
     }
 };
 
-BEAST_DEFINE_TESTSUITE_MANUAL(recover_big,nudb,beast);
-
 } // test
 } // nudb
 } // beast

beast/nudb/tests/store_test.cpp

@@ -124,7 +124,11 @@ public:
     {
         enum
         {
+        #ifndef NDEBUG
+            N =             5000 // debug
+        #else
             N =             50000
+        #endif
             ,block_size =   256
         };