file: support close function pointer

src/runtime/file.cpp

@@ -824,8 +824,7 @@ extern "C" void PyFile_SetFP(PyObject* _f, FILE* fp) noexcept {
 }
 
 extern "C" PyObject* PyFile_FromFile(FILE* fp, char* name, char* mode, int (*close)(FILE*)) noexcept {
-    RELEASE_ASSERT(close == fclose, "unsupported");
-    return new BoxedFile(fp, name, mode);
+    return new BoxedFile(fp, name, mode, close);
 }
 
 extern "C" FILE* PyFile_AsFile(PyObject* f) noexcept {
@@ -1082,8 +1081,8 @@ void fileDestructor(Box* b) {
     assert(isSubclass(b->cls, file_cls));
     BoxedFile* self = static_cast<BoxedFile*>(b);
 
-    if (self->f_fp)
-        fclose(self->f_fp);
+    if (self->f_fp && self->f_close)
+        self->f_close(self->f_fp);
     self->f_fp = NULL;
 }