[minor] panic on agent init err if foreground mode
[minor] panic on agent init err if foreground mode

The comment said "if in foreground mode, don't retry, just panic", but
fhe if condition only checked for debug, no foreground.
debug -> foreground, but you can run the mig agent in foreground without
debug mode.

yvesago/mig,ameihm0912/mig,jboyer2012/mig,mozilla/mig,ameihm0912/mig,sunnygkp10/mig,mozilla/mig,rezen/mig,rezen/mig,sunnygkp10/mig,jboyer2012/mig,sunnygkp10/mig,yvesago/mig,jboyer2012/mig,therealkbhat/mig,ameihm0912/mig,yvesago/mig,therealkbhat/mig,mozilla/mig,vladimirdiaconescu/mig,mozilla/mig,sunnygkp10/mig,yvesago/mig,mozilla/mig,vladimirdiaconescu/mig,rezen/mig,vladimirdiaconescu/mig,rezen/mig,jboyer2012/mig,therealkbhat/mig,vladimirdiaconescu/mig,therealkbhat/mig