program: only reuse constants of the same size and value

program: only reuse constants of the same size and value

When reusing an existing constant, make sure not only the value but also
the size is the same. We then also need to make a name based on the size
and value so that we can store the same value for different sizes.

Fixes problem with the bayer functions that used 255 as a 16 and 8 bit
constant. This was not detected in the unit test because both the backup
and asm functions do the same error, but it could be seen when a new
backup function was checked against a older ORC.