add config to sqlite3 to be SQLITE_CONFIG_SERIALIZED (#428)

Author: dejan2k

Leanplum-SDK/Classes/Utilities/LPDatabase.m

@@ -50,6 +50,11 @@ - (id)init
 - (sqlite3 *)initSQLite
 {
     const char *sqliteFilePath = [[LPDatabase sqliteFilePath] UTF8String];
+    
+    sqlite3_shutdown();
+    sqlite3_config(SQLITE_CONFIG_SERIALIZED);
+    sqlite3_initialize();
+        
     int result = sqlite3_open_v2(sqliteFilePath, &sqlite, SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE | SQLITE_OPEN_FULLMUTEX, NULL);
     if (result != SQLITE_OK) {
         [self handleSQLiteError:@"SQLite fail to open" errorResult:result query:nil];