Record total dependency scan run-time
Record total dependency scan run-time

This metric includes, for all nodes+edges needed for the selected
targets:
 * stat'ing input paths
 * evaluating and hashing command-lines
 * adding node<->edge links for implicit deps from the depslog and
   depfiles

Bug: none
Test: Run "-d stats <target>" and check the dep scan run-time
Change-Id: I132fcb1ffae2be249f19381d0d4f44436027641f

mydongistiny/ninja,mydongistiny/ninja,mydongistiny/ninja,mydongistiny/ninja