Free pending named positions on partial-argument compile errors

[iliaal]

A partial application that uses a named placeholder (foo(x: ?, ...)) lazily allocates a named-positions table in zend_compile_args_ex, consumed only after argument compilation succeeds. A following argument that is itself a compile error (a positional or unpack after the named placeholder, or a misplaced variadic placeholder) longjmps out of the function before the table is consumed and leaks it.

This frees the table before the four reachable errors. The leak is on a zend_bailout path, so ZEND_MM's leak reporter never sees it; it shows only under valgrind/ASAN. Verified with USE_ZEND_ALLOC=0 valgrind: 376 bytes to 0 on foo(x: ?, ?), and 0 on the unpack, named-after-variadic, and variadic-twice variants. The added test exercises the path for CI valgrind; the error output is identical before and after, so it is a path check, not an output red/green.

[ndossche]

I don't think we ever clean up memory on a 'noreturn' compile error; since the heap is destroyed anyway.

[iliaal]

Yeah, it might be not necessary. Fairly simple fix though, I'll let @Arnaud-L weigh in here, if we agrees this is not necessary I'll close

[arnaud-lb]

I found no example of freeing before _noreturn, so for consistency I think that it would be better to not make this change

[iliaal]

Ok