Typofix.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>

rts/LdvProfile.c

@@ -212,7 +212,7 @@ processChainForDead( bdescr *bd )
  * current garbage collection.  This function is called from a garbage
  * collector right before tidying up, when all dead closures are still
  * stored in the heap and easy to identify.  Generations 0 through N
- * have just beed garbage collected.
+ * have just been garbage collected.
  * ----------------------------------------------------------------------- */
 void
 LdvCensusForDead( nat N )