More descriptive name for bpf_filter1().

Call it bpf_filter_with_aux_data(), to better indicate what it does.

Also expand some comments and clean up white space a bit.
Get rid of unused variable.

Also clean up white space a bit.
Move the socket ops out of gencode.c.

Instead, do it in pcap-linux.c, and have it set a flag in the pcap_t
structure to indicate to the code in gencode.c that it needs to generate
special VLAN-handling code.
<linux/filter.h> needs <linux/types.h>, and it's not automatically included.

This fixes build errors on, for example, a Red Hat system with a 2.6.9
kernel.
Not all systems have <stdint.h>

Don't include it, and use u_intXX_t, which we arrange to be defined,
rather than uintXX_t.
There's no pcap_t argument to code generator routines.

Use the global bpf_pcap instead.
Use u_short rather than u_int16_t; that's what we do elsewhere.

u_int16_t is not guaranteed to be defined when this is included by
applications (for example, tcpdump).