{linux,bsd}-user: Update ts_tid after fork()

{linux,bsd}-user: Update ts_tid after fork()

Currently ts_tid contains the parent tid after fork(), which is not
correct. So far it has not affected anything, but the upcoming
follow-fork-mode child support relies on the correct value, so fix it.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20240219141628.246823-4-iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240305121005.3528075-5-alex.bennee@linaro.org>