OSV-2020-1741 Heap-use-after-free in zend_assign_to_variable

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=25601 Crash type: Heap-use-after-free READ 1 Crash state: zendassigntovariable zendstdwriteproperty ZENDASSIGNOBJSPECCVCONSTOPDATAVARHANDLER...