Mirror tcg_out_movi in having a TYPE parameter.  This allows x86_64
to perform the move at the proper width, which may elide a REX prefix.

Introduce a TCG_TYPE_REG enumerator to represent the "native width"
of the host register, and to distinguish the usage from "pointer data"
as represented by the existing TCG_TYPE_PTR.

Update all targets to match.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>