CFFI val_ocallN does not match its public argument-vector signature #228

The public CFFI declaration for val_ocallN takes four arguments: object, field id, value pointer array, and argument count. The runtime implementation has only three parameters and treats the pointer-array argument as one Haxe object value.

Regression coverage first: test/regression/CffiObjectCallVector in the existing Main.hx/build.hxml/stdout.txt layout. Resolve val_ocallN through the actual hx_cffi export table and call it using the signature from CFFIAPI.h. Use a native sentinel callback that reports the number of arguments it receives without reading the malformed value. Exercise zero, one and three arguments.

Confirmed on Linux x86_64 with Haxe 4.3.3:

requested 0 arguments, received 1
requested 1 arguments, received 1
requested 3 arguments, received 1

The one-argument case matching by count does not establish correctness: it receives the value-array address rather than the array's element. The sentinel deliberately does not dereference that value.

include/hx/CFFIAPI.h declares:

DEFFUNC_4(value,val_ocallN,value,int,value *,int)

src/hx/CFFI.cpp implements:

hx::Object *val_ocallN(hx::Object *arg1, int arg2, hx::Object *arg3)

It then dispatches the field with __run(Dynamic(arg3)) on API levels below 500, or a single-argument invoker call on API level 500. It never reads the argument count or packs the value vector. hx_cffi returns that implementation under the public val_ocallN name.

Make the implementation match the exported declaration and dispatch the requested argument vector, as val_callN does. Test argument contents, zero arguments, larger arities, thrown callbacks and null receivers. Include both static-link and dynamically resolved calls so declaration/export drift is caught. The current functional reproduction is API level 430; the API level 500 branch has the same source-level mismatch but was not executed in this probe.

This affects native extensions calling object fields through CFFI. No runtime implementation changes are included.