SQL/SQLite: fix compilation with SQLite < 3.40.0

sqlite3_filename was indroduced with SQlite 3.40.0 so we have to define
it by our own for older versions.

Task-number: QTBUG-107120
Fixes: QTBUG-116572
Change-Id: I3186e58c3538135dc01a1be9cc54621699d1cec1
Reviewed-by: Liang Qi <liang.qi@qt.io>

src/plugins/sqldrivers/sqlite/qsql_sqlite_vfs.cpp

@@ -12,6 +12,9 @@
 #ifndef PATH_MAX
 #  define PATH_MAX FILENAME_MAX
 #endif
+#if SQLITE_VERSION_NUMBER < 3040000
+typedef const char *sqlite3_filename;
+#endif
 
 namespace {
 struct Vfs : sqlite3_vfs {