Should examples be marked as no_run instead of ignore?

[TDHolmes]

Coming out of #269 , I'm wondering if it makes sense to change all examples from ignore to just no_run. This would ensure they all still compile. I can take a look at this, but wanted to file a radar so I don't forget / if I forget at least I wrote it down 😅

[japaric]

the examples marked as ignore depend on crates like cortex-m. having those target-specific crates as dev-dependencies could make the CI more complex (e.g. if we want to avoid building them on x86). I think it would be preferable to tweak the code to not depend on the cortex-m crates while still indicating "this function is the entry point", "this function is a signal/interrupt handler", etc.