Move the tcg_temp_free_* and tcg_temp_ebb_new_* declarations
and inlines to the new header.  These are private to the
implementation, and will prevent tcg_temp_free_* from creeping
back into the guest front ends.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>