tree-optimization/118634 - improve cunroll dump

tree-optimization/118634 - improve cunroll dump

We no longer subtract the estimated eliminated number of instructions
from the estimated size after unrolling we print - this is a bit
confusing when comparing dumps to previous releases.  The following
changes the dump from

  Estimated size after unrolling: 42

to

  Estimated size after unrolling: 42-12

for the testcase in the PR.

	PR tree-optimization/118634
	* tree-ssa-loop-ivcanon.cc (try_unroll_loop_completely):
	Dump the number of estimated eliminated insns.