Fix NINJA_STATUS %e on dumb terminals
Fix NINJA_STATUS %e on dumb terminals

PR #999 made dumb terminals only output when edges
finish. BuildStatus::overall_rate_ stopwatch is only initialized to the
current time when PrintStatus is called with finished_edges_ == 0, but
on a dumb terminal it will be called for the first time when
finished_edge_ = 1, which results in very long elapsed times:
NINJA_STATUS="[%r processes, %f/%t @ %o/s : %es ] "
[0 processes, 2/2 @ 0.0/s : 1461869902.367s ]

Reset the stopwatches in BuildEdgeFinished before finshed_edges_ is
incremented instead.

moroten/ninja,maruel/ninja,mohamed/ninja,nicolasdespres/ninja,iwadon/ninja,mydongistiny/ninja,ndsol/subninja,sxlin/dist_ninja,AoD314/ninja,sxlin/dist_ninja,sxlin/dist_ninja,sgraham/ninja,ndsol/subninja,Qix-/ninja,nico/ninja,vvvrrooomm/ninja,nafest/ninja,mydongistiny/ninja,mydongistiny/ninja,moroten/ninja,moroten/ninja,bradking/ninja,maruel/ninja,bradking/ninja,fuchsia-mirror/third_party-ninja,bradking/ninja,iwadon/ninja,atetubou/ninja,ninja-build/ninja,atetubou/ninja,sxlin/dist_ninja,Maratyszcza/ninja-pypi,juntalis/ninja,martine/ninja,AoD314/ninja,sgraham/ninja,juntalis/ninja,AoD314/ninja,nicolasdespres/ninja,atetubou/ninja,lizh06/ninja,maruel/ninja,nicolasdespres/ninja,mgaunard/ninja,mgaunard/ninja,mohamed/ninja,moroten/ninja,atetubou/ninja,Maratyszcza/ninja-pypi,sgraham/ninja,sxlin/dist_ninja,fuchsia-mirror/third_party-ninja,ninja-build/ninja,lizh06/ninja,mgaunard/ninja,vvvrrooomm/ninja,Qix-/ninja,nafest/ninja,ninja-build/ninja,mohamed/ninja,martine/ninja,iwadon/ninja,fuchsia-mirror/third_party-ninja,nico/ninja,mydongistiny/ninja,Qix-/ninja,nico/ninja,iwadon/ninja,sxlin/dist_ninja,mgaunard/ninja,ndsol/subninja,juntalis/ninja,nafest/ninja,Maratyszcza/ninja-pypi,nicolasdespres/ninja,sxlin/dist_ninja,ninja-build/ninja,maruel/ninja,lizh06/ninja,juntalis/ninja,AoD314/ninja,martine/ninja,sgraham/ninja,vvvrrooomm/ninja,lizh06/ninja,nico/ninja,bradking/ninja,vvvrrooomm/ninja,martine/ninja,fuchsia-mirror/third_party-ninja,Qix-/ninja,nafest/ninja,Maratyszcza/ninja-pypi,ndsol/subninja,mohamed/ninja