[development] need a standard for contrib node build_mode constants

[Earl Miles]

Karoly Negyesi wrote:
> To the contrary, Peter's proposition makes a very good standard to
> avoid collisions, it's actually better than strings IMO.

Hardly. You have an int that has no real meaning and then a string 
anyway, which is the define. The *only* improvement is that in theory a 
32 bit int is slightly faster to look up via index.