Fixed compiler warnings

ext/mbstring/libmbfl/filters/mbfilter_cp51932.c

@@ -111,7 +111,7 @@ const struct mbfl_convert_vtbl vtbl_wchar_cp51932 = {
 int
 mbfl_filt_conv_cp51932_wchar(int c, mbfl_convert_filter *filter)
 {
-	int c1, s, w, n;
+	int c1, s, w;
 
 	switch (filter->status) {
 	case 0:

ext/pdo_firebird/firebird_driver.c

@@ -38,8 +38,10 @@ static int firebird_alloc_prepare_stmt(pdo_dbh_t*, const char*, long, XSQLDA*, i
 /* map driver specific error message to PDO error */
 void _firebird_error(pdo_dbh_t *dbh, pdo_stmt_t *stmt, char const *file, long line TSRMLS_DC) /* {{{ */
 {
+#if 0
 	pdo_firebird_db_handle *H = stmt ? ((pdo_firebird_stmt *)stmt->driver_data)->H 
 		: (pdo_firebird_db_handle *)dbh->driver_data;
+#endif
 	pdo_error_type *const error_code = stmt ? &stmt->error_code : &dbh->error_code;
 	
 #if 0

ext/pdo_pgsql/pgsql_statement.c

@@ -215,8 +215,9 @@ stmt_retry:
 static int pgsql_stmt_param_hook(pdo_stmt_t *stmt, struct pdo_bound_param_data *param,
 		enum pdo_param_event event_type TSRMLS_DC)
 {
-	pdo_pgsql_stmt *S = (pdo_pgsql_stmt*)stmt->driver_data;
 #if HAVE_PQPREPARE
+	pdo_pgsql_stmt *S = (pdo_pgsql_stmt*)stmt->driver_data;
+
 	if (S->stmt_name && param->is_param) {
 		switch (event_type) {
 			case PDO_PARAM_EVT_FREE: