MFH: r539884

databases/py-mysqlclient: revert gc threaded patch

It caused python sigabort with a "GC object already tracked" message in singlethreaded app.
This happens only with a fetchmany() on a streaming cursor, MySQLdb.cursors.SSCursor.

PR: 246313
Reported by: Jeroen Pulles <jeroen.pulles@gmail.com>

Approved by: ports-secteam (joneum)