Remove a superfluous comment.

Benchmarks have shown that (collision buckets)/(set size) ranges
from 10%-25%, so there's no need to tweak the hash table size.

src/ph.c

@@ -127,16 +127,6 @@ lg(unsigned n)
 	return (lg);
 }
 
-/*
- * Note: there's potential here to use parameters so that users can decide
- * about a time/space tradeoff. It would allow bits to be increased up to
- * a limit, increasing the size of the hash table and making it sparser
- * (that's space). Do so until the expected collision rate falls below a
- * threshold (time), or until an upper bound on the table size is reached.
- *
- * An estimate for the expected number of collisions is:
- * (n * (n - 1)) >> (bits + 1)
- */
 static uint32_t
 getsz(unsigned n)
 {