Revamp the way the DBSTAT virtual table is registered.

FossilOrigin-Name: 4e6520159e729b6ea96ccdb14f0ecb00a0ff7cbd
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 7b9542a..d809245 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3867,4 +3867,8 @@
 int sqlite3ThreadJoin(SQLiteThread*, void**);
 #endif
 
+#if defined(SQLITE_ENABLE_DBSTAT_VTAB) || defined(SQLITE_TEST)
+int sqlite3DbstatRegister(sqlite3*);
+#endif
+
 #endif /* _SQLITEINT_H_ */