zend_runtime_jit() prevents concurrent compilation with
zend_shared_alloc_lock(), but this doesn't prevent blocked threads from
trying to compile the function again after they acquire the lock.
In the case of GH-19889, one of the function entries is compiled with
zend_jit_handler(), which fails when the op handler has already been replaced by
a JIT'ed handler.
Fix by marking compiled functions with a new flag ZEND_FUNC_JITED, and
skipping compilation of marked functions. The same fix is applied to
zend_jit_hot_func().
Fixes GH-19889
Closes GH-19971
359ad80c4a