emulators/skyeye: Unbreak build with GCC 10 (-fno-common default)

/usr/local/bin/ld: ./utils/libutils.a(skyeye_arch.o):/wrkdirs/usr/ports/emulators/skyeye/work/skyeye-1.2.5_REL/utils/config/skyeye_config.h:274: multiple definition of `skyeye_config'; skyeye.o:/wrkdirs/usr/ports/emulators/skyeye/work/skyeye-1.2.5_REL/./utils/config/skyeye_config.h:274: first defined here
/usr/local/bin/ld: ./utils/libutils.a(skyeye_config.o):/wrkdirs/usr/ports/emulators/skyeye/work/skyeye-1.2.5_REL/utils/config/skyeye_config.h:274: multiple definition of `skyeye_config'; skyeye.o:/wrkdirs/usr/ports/emulators/skyeye/work/skyeye-1.2.5_REL/./utils/config/skyeye_config.h:274: first defined here
/usr/local/bin/ld: ./utils/libutils.a(skyeye_options.o):/wrkdirs/usr/ports/emulators/skyeye/work/skyeye-1.2.5_REL/utils/config/skyeye_config.h:274: multiple definition of `skyeye_config'; skyeye.o:/wrkdirs/usr/ports/emulators/skyeye/work/skyeye-1.2.5_REL/./utils/config/skyeye_config.h:274: first defined here
[...]

http://package18.nyi.freebsd.org/data/121amd64-default-PR244494/2020-06-10_18h04m44s/logs/errors/skyeye-1.2.5_7.log

PR: 246700