Linux major/minor conversion not entirely correct

[John E Hein]

Ed Schouten wrote at 16:47 +0200 on Jun  2, 2008:
 > > Where does the magic number 136 come from?
 > 
 > Linux uses major numbers 136,137,138,... for PTY's.

We should probably point that out in a comment &/or #define.

I've heard no plans to change the device numbering scheme in linux in
the near future.  So this magic number should likely be stable for
some time to come, correct?