linux-user: Rename cpu_clone_regs to cpu_clone_regs_child

linux-user: Rename cpu_clone_regs to cpu_clone_regs_child

We will need a target-specific hook for adjusting registers
in the parent during clone.  To avoid confusion, rename the
one we have to make it clear it affects the child.

At the same time, pass in the flags from the clone syscall.
We will need them for correct behaviour for Sparc.

Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20191106113318.10226-10-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>