gh-150942: Speed up IOBase.readlines - #155304
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This PR optimizes
_io.IOBase.readlines()by using_PyList_AppendTakeRef()when adding lines to the result list.Previously, each line was added with
PyList_Append(), which creates anextra temporary reference. The new code transfers the existing reference
directly to the result list, avoiding an unnecessary reference-count
increment/decrement pair.
The order of operations is unchanged: the line is added before its length
is inspected, preserving the prior behavior.
Tests:
./python.exe -m test --verbose test_io