My new iMac (2017, running 10.12.5) has by default F14/F15 bound to control the display brightness. I can't find any way to disable them, which means that binding them to other functions doesn't work. Using a third party tool like Keyboard Maestro can map the keys, but doesn't override the brightness adjustment, so you get two functions at once.
In my research it seems that some versions of Mac OS had a Display option under Keyboard Shortcuts that had the applicable options:
Unfortunately I don't have that.
So my question is: How do I get that Display section back, or how do I unbind the decrease/increase display brightness shortcuts?