Add the full structure-return (sret) convention to the hand source so
stage-2 generates correct IR for functions/methods that return tyRecord:
- EmitMethodDef/EmitFuncDef: declare record-returning functions as void
with a hidden first param `l %_par__sret`; initialise %_var_Result
from it; emit bare `ret` at exit.
- IsRecordCall / EmitRecordCallSret: detect record-returning call
expressions (TFuncCallExpr, TMethodCallExpr, TFieldAccessExpr) and
emit them with the sret address as the first argument. Handles the
IsImplicitSelf path with correct Self+offset pointer arithmetic.
- EmitRecordCopy / EmitRecordReleaseFields: field-by-field ARC-correct
copy and release helpers for record types.
- EmitAssignment tyRecord branch: for record-typed lhs, either call
EmitRecordCallSret (when the rhs is a call) or EmitRecordCopy.
- ImplicitSelfField tyRecord branch in EmitAssignment: same logic for
assignments to record fields reached via implicit Self.
- TIdentExpr IsImplicitSelf tyRecord fix: return the field address
rather than loading through it (callers need the address for copies).
- TIdentExpr local/global record variable fix: return VarRef address
directly instead of an extra loadl.
All fixes mirror what the real multi-file source already had; this
brings the hand source to parity for record-return code generation.
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