Yes, smoking of cannabis is considered a form of smoking for the purposes of both the interior and exterior smoking provisions of the LEED Prerequisite Environmental Tobacco Smoke Control.
Secondhand cannabis smoke has been shown to contain many of the same chemicals and carcinogens as secondhand tobacco smoke [1].
[1] Moir D, Rickert WS, Levasseur G, et al. A Comparison of Mainstream and Sidestream Marijuana and Tobacco Cigarette Smoke Produced under Two Machine Smoking Conditions. American Chemical Society. 2008;21:494-502.