Start using config.h, and use it for HAVE_PCAP_NEXT_EX.

In #110, @vodik reported that HAVE_PCAP_NEXT_EX was unused. This
changeset does the following:

* Remove uint8_t and friends from configure.ac because the resulting
  defines (`define uint8_t unsigned char`) conflict with typedefs from
  `netinet/in.h`.
* Include `config.h` from `prepare_pcap.c`.
* Fix so HAVE_PCAP_NEXT_EX is defined in config.h if available.

TODO: We should move HAVE_EPOLL from the Makefile.am CFLAGS addition to
config.h inclusion as well.
So many clang analzyer problems arise from expecting ERROR_NO to bail
process_command doesn't check argument existance

Should process_command not get an argument, we get NULL deference errors
inside process_reset, process_dump, process_trace, and process_set.

Caught by clang-analyzer.
Defencive check for key when doing AKAv1-MD5

It is possible to do AKAv1-MD5 and get a null dereference if aka_K
isn't provided. One of the auth tests triggered this defect even though
it was doing MD5 (static analyzer won't do the parsing of the algorithm
field).

Cause by clang-analyzer.
Drop dead assignments/increments/initialization

Caught by clang-analyzer.
Use-after-free if sendCmdBuffer fails

The call class deletes itself on failure so we really can't continue
with the method. Needs to abort immediately. (Seriously, the class is
calling delete this? That's just asking for pain).

Caught by clang-analyzer.
You cannot call computeStat after abortCall.

call::abortCall also does delete this. Which means you can't call
call::computeStat safely after the fact. Another use-after-free bug.

Caught by clang-analyzer.
Correct the return from connect_to_peer

connect_to_peer is returning stack-allocated memory. The stack allocated
T_peer_infos structure technically means a copy from the iterator,
meaning that we can't really return the address of peer_socket safely.

Caught by clang-analyzer.
Fix garbage/undefined load on E_Message_Server_IP

SOCK_ADDR_SIZE can't be used here because server_sockaddr. The
structure is uninitialized so we can't look up the ss_family.

It's just fine calling getsockname with sizeof the full
sockaddr_storage structure, the macro is overkill. I wonder if that's
the case in other places.

Caught by clang-analyzer.
Fix potential memory leak after second strtok

Memory is allocated before we know if anything is there to copy into
it. Flat out rewritten.

Caught by clang-analyzer.
Fix potential memory leak when HAVE_PCAP_NEXT_EX isn't defined

We malloc pkthdr, we must free it too.

Caught by clang-analyzer.
Free the existing M_regularExpression if its already set

Potential memory leak. Passing P_value into regcomp to placate the
static analyzer.

Caught by clang-analyzer.
Bail out if dest is NULL

The currently protective check isn't sufficient. Bail out to avoid
invalid memory access.
Check if call_socket is NULL before dereferencing

Static analyzer is finding that its possible to get a NULL call_socket
here, so lets be defencive and check for it.

Caught by clang-analyzer.
Check if play_args is NULL before dereferencing

Caught by clang-analyzer.
Fix NULL dereference in xp_open_element

Bail outright if xp_find_start_tag_end fails. The if (ptr) check here
isn't sufficient because later on we'll hit ptr++.

Caught by clang-analyzer.
Merge pull request #111 from SIPp/fix/use_config_h_use_pcap_next_ex

Start using config.h, and use it for HAVE_PCAP_NEXT_EX.
Fix older autoconf/automake that don't work with AC_CONFIG_MACRO_DIR.

Fixes #114. Patch by @kvishnivetsky.
Typo.
Cleanup of useless unused argument void casts in C++ files.

Perhaps we should've done this instead:

    //-------------------------------------------------------------------------
    //  Suppress nuisance compiler warnings. Yes, each compiler can already
    //  do this, each differently! VC9 has its UNREFERENCED_PARAMETER(),
    //  which is almost the same as the SUPPRESS_UNUSED_WARNING() below.
    //
    //  We append _UNUSED to the variable name, because the dumb gcc compiler
    //  doesn't bother to tell you if you erroneously _use_ something flagged
    //  with __attribute__((unused)). So we are forced to *mangle* the name.
    //-------------------------------------------------------------------------
    #if defined(__cplusplus)
    #define UNUSED(x)       // = nothing
    #elif defined(__GNUC__)
    #define UNUSED(x)       x##_UNUSED __attribute__((unused))
    #else
    #define UNUSED(x)       x##_UNUSED
    #endif
    ...
    int foo(int UNUSED(bar)) { ... }