min/max and all that jazz

[Duncan Sands]

gcc has a warning option -Wsign-compare (not turned on by -Wall):

`-Wsign-compare'
     Warn when a comparison between signed and unsigned values could
     produce an incorrect result when the signed value is converted to
     unsigned.  This warning is also enabled by `-W'; to get the other
     warnings of `-W' without this warning, use `-W -Wno-sign-compare'.

This might pick up some errors of the kind the new min/max macros
are trying to catch...

Duncan.

PS: please CC any comments to me, since I'm not subscribed to the list.