Who killed He-Man? This was the question on Hollywood’s mind when “Masters of the Universe,” the latest take on the beloved Mattel property that began in 1982, wound up face-planting this month. On paper, it had the makings of a hit. The property boasts a fanbase that grew up on the combination toy line/animated series that thrived in the deregulated Reagan ’80s, the same period in which “Transformers” thrived. An attempt at a live-action adapta…