misc: don't os_exit(1) causing core on SIGINT
misc: don't os_exit(1) causing core on SIGINT

It's not typical for a program to core when it receives a SIGINT, so
keep this from happening.

Type: fix
Signed-off-by: Christian E. Hopps <b3a0225f102824409da8f538c6e224da04e786c9@chopps.org>
Change-Id: I2c15985a57e6ea898ff05c4001e4b30b41154eba

vpp-dev/vpp,vpp-dev/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,vpp-dev/vpp