Merge pull request #6039 from Goober5000/percent_ships_scanned #601

Job	Run time
Linux (Debug, gcc-9)	13m 29s
Linux (Debug, gcc-13)	12m 40s
Linux (Debug, clang-16)	13m 14s
Linux (Release, gcc-9)	9m 59s
Linux (Release, gcc-13)	10m 36s
Linux (Release, clang-16)	14m 19s
Linux (Debug, gcc-13, -DFSO_BUILD_WITH_OPENGL=OFF -DFSO_BUILD_WITH_VULKAN=OFF)	11m 49s
Linux (Release, gcc-13, -DFSO_BUILD_WITH_OPENGL=OFF -DFSO_BUILD_WITH_VULKAN=OFF)	11m 33s
	1h 37m 39s

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