accel/tcg: move jit thread manipulation into do_tb_phys_invalidate

To invalidate a TB on MacOS we need to enable write access to the JIT
buffer. We were doing this for tb_phys_invalidate__locked but that is
not the only path into do_tb_phys_invalidate. Move the manipulation
into the shared function that does the work.

As a result we can drop the tb_phys_invalidate__locked function and
update the calls directly.

This enables watchpoints to work in MacOS TCG guests.

Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3444
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20260526110243.470002-5-alex.bennee@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
(cherry picked from commit 78420b59f0fe227605bd67e1e232df9dc1ec539b)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>