’feenableexcept’ doesn’t exist on OSX.

[davidbuzz]

please cherry-pick this tiny fix:
davidbuzz/ardupilot-mega-buzz@bf8dc3a

[davidbuzz]

try compiling diydrones/master on OSX, and this error occurs:
‘make sitl’ gives me this: “/Users/buzz/UAV/ardupilot/libraries/AP_HAL_AVR_SITL/Scheduler.cpp:213:9: error: use of undeclared identifier 'feenableexcept'; did you mean 'feraiseexcept'?"
the above fixes it.

[rmackay9]

I'll bet doing this as a PR will make it more likely that it gets into master.

[OXINARF]

This has been fixed. Although AVR doesn't exist anymore, current SITL also uses feenableexcept. A workaround for OSX was included: https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_Common/missing/fenv.h