Add the sqlite3_status64() interface.  Make the new interface and the legacy
sqlite3_status() both atomic and threadsafe.  Check threadsafety using
assert()s.

FossilOrigin-Name: 1ce8e8fa4b866aafa12b1da0eb4d02321af9293e
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 9e174d6..78945c1 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3097,10 +3097,15 @@
   int sqlite3MutexEnd(void);
 #endif
 
-int sqlite3StatusValue(int);
-void sqlite3StatusAdd(int, int);
+sqlite3_int64 sqlite3StatusValue(int);
+void sqlite3StatusUp(int, int);
+void sqlite3StatusDown(int, int);
 void sqlite3StatusSet(int, int);
 
+/* Access to mutexes used by sqlite3_status() */
+sqlite3_mutex *sqlite3Pcache1Mutex(void);
+sqlite3_mutex *sqlite3MallocMutex(void);
+
 #ifndef SQLITE_OMIT_FLOATING_POINT
   int sqlite3IsNaN(double);
 #else