Patch fold-const.c add missing return non-void function

[Jeffrey A Law]

  In message <199802261324.NAA00198@iron.rcp.co.uk>you write:
  > 
  > 
  > 
  > * fold-const.c (fold-range-test): added missing return in non-void   
  > function
Thanks.  I fixed this in a slightly, but equivalent way.

jeff