Removes comment for find_package(PCAP)

Ubertooth would not build without this enabled on debian 7.7:

CMakeFiles/ubertooth-btle.dir/ubertooth-btle.c.o: In function `main':
ubertooth-btle.c:(.text+0x439): undefined reference to `h_pcap_le'
ubertooth-btle.c:(.text+0x44a): undefined reference to `h_pcap_le'
ubertooth-btle.c:(.text+0x493): undefined reference to `h_pcap_le'
ubertooth-btle.c:(.text+0x4a4): undefined reference to `h_pcap_le'
collect2: error: ld returned 1 exit status
make[2]: *** [ubertooth-tools/src/ubertooth-btle] Error 1
make[1]: *** [ubertooth-tools/src/CMakeFiles/ubertooth-btle.dir/all] Error 2
make: *** [all] Error 2