Reduce some of GCC 7's nagging

[CounterPillow]

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Disable -Wimplicit-fallthrough using fallthrough comments, since we can't use C++17 attributes.

Also disable -Wattributes in embree, since it generates a lot of warnings from that.

[tunabrain]

Thanks for that! Is it possible to just use -Wno-implicit-fallthrough instead of modifying tinyformat? I'd like to avoid modifying third-party libraries, since those changes will be overwritten when the library is updated.

[nemequ]

Better yet, why not just update tinyformat? This seems to be fixed already there…

[CounterPillow]

Well, you are commenting over a year later

[nemequ]

Originally I was going to suggest fixing tinyformat instead of just disabling the warning. It's an easy patch.