Add tcg_set_insn_param as a mechanism to modify an insn
parameter after emiting the insn. This is useful for icount
and also for embedding fault information for a specific insn.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1461931684-1867-2-git-send-email-edgar.iglesias@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>