A Nil Python generator called with a str literal segfaults

def gen(s):
    yield s
for x in gen("hi"):      # segfault, every target
    print(x)

These all worked: gen(t) with a str variable, gen("hi" + ""), gen(5), gen(None) and a tuple. The boundary is the parameter's stored kind: 23 (AnsiString) for the literal call, and 22 (Variant, carried in a heap cell) otherwise. This is the Nil Python twin of bug-a-a-string-literal-passed-to-a-stackless-generator-is-stored-without-being-materialised.

Fix

PasGenArgNeedsStrTemp no longer excludes Nil Python. PyBuildGeneratorValue materialises the argument through an AnsiString temp in the same way, and now takes its slot offsets from GenArgSlotOff, like the for desugar.

Test

test/test_nilpy_cross32_values.py (the str-literal block): a row in test-core and rows in the three cross targets. Measured wrong with pin v446 (stable_linux_amd64/default/stable_pinned) on 2026-09-28.