Description:
------------
If FFI::cast() fails with FFI\Exception "attempt to cast to larger
type", a zend_ffi_cdata struct is leaked.


Test script:
---------------
<?php
try {
    FFI::cast('char[10]', FFI::new('char[1]'));
} catch (FFI\Exception $ex) {
    echo $ex->getMessage(), PHP_EOL;
}


Expected result:
----------------
attempt to cast to larger type


Actual result:
--------------
attempt to cast to larger type
[Wed Oct 30 17:10:23 2019]  Script:  '/mnt/d/git/php/bug78761.php'
/mnt/d/git/php/php-src/ext/ffi/ffi.c(241) :  Freeing 0x00007f0f67081180 (88 bytes), script=/mnt/d/git/php/bug78761.php
=== Total 1 memory leaks detected ===