tcg: Change parameters for tcg_target_const_match

Change the return value to bool, because that's what is should
have been from the start.  Pass the ct mask instead of the whole
TCGArgConstraint, as that's the only part that's relevant.

Change the value argument to int64_t.  We will need the extra
width for 32-bit hosts wanting to match vector constants.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>