[flang][runtime] Complete partial output records when positioning/closing...

[flang][runtime] Complete partial output records when positioning/closing after non-advancing output

Before positioning or closing a unit after a non-advancing output statement
has left a partial record in its buffer, complete the record by calling
AdvanceRecord().  Fixes https://github.com/llvm/llvm-project/issues/59761.

Differential Revision: https://reviews.llvm.org/D151134