Remove unneeded copy and cast in "camera.cpp" #837

Job	Run time
clickable (Debug, amd64, glew)	17m 6s
clickable (Debug, amd64, sdl)	16m 35s
clickable (Debug, armhf, glew)	21m 52s
clickable (Debug, armhf, sdl)	15m 4s
clickable (Release, amd64, glew)	25m 4s
clickable (Release, amd64, sdl)	21m 4s
clickable (Release, arm64, glew)	19m 32s
clickable (Release, arm64, sdl)	15m 48s
clickable (Release, armhf, glew)	14m 58s
clickable (Release, armhf, sdl)	16m 41s
	3h 3m 44s

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