arm32: a def stored into a Variant field is tagged int

test/test_nilpy_callable_field_all_shapes.npy, ..._call_returns.npy and ..._wide_arity.npy matched x86-64 on i386 and aarch64, and differed on arm32.

Fix

In ir_codegen_arm32.inc, both arms now override the tag with VT_CALLABLE_TAG when IRSrcIsCallable is true, the same line every other backend has.

Test

Rows for the three tests in test-arm32. Measured wrong with pin v446 (stable_linux_amd64/default/stable_pinned) on 2026-09-28.