[tz] coding style for tzcode?

[Paul Eggert]

The code has always been somewhat eclectic in style.  As it gets more 
complicated the 8-character indenting has had problems scaling, and I've been 
using 2-character indenting in new changes when that doesn't involve reindenting 
much existing code, and sometimes 4-character to insert an intermediate level of 
indentation without reindenting much else.  Reformatting the code to a 
particular style or indentation level would make it harder to compare versions.