Fix compiliation issue on FreeBSD

src/fg_pcap.c: In function 'fg_pcap_work':
src/fg_pcap.c:295: error: label at end of compound statement
*** [src/flowgrindd-fg_pcap.o] Error code 1

The label should point to a statement. C mandates this:

(C99, 6.8.1 Labeled statements p4) " Any statement may be preceded by a
prefix that declares an identifier as a label name."