Fix warnings related to mismatch of function parameters

[miconda]

Compiling latest devel version on MacOS 14.1 resulted in warnings:

In file included from capture.c:39:
./capture.h:316:1: warning: a function declaration without a prototype is deprecated in all versions of C and is treated as a zero-parameter prototype in C2x, conflicting with a subsequent definition [-Wdeprecated-non-prototype]
capture_launch_thread();
^
capture.c:1042:1: note: conflicting prototype is here
capture_launch_thread(capture_info_t *capinfo)
^
1 warning generated.
  CC       sngrep-address.o
  CC       sngrep-packet.o
  CC       sngrep-sip.o
sip.c:352:27: warning: passing arguments to 'msg_create' without a prototype is deprecated in all versions of C and is not supported in C2x [-Wdeprecated-non-prototype]
    if (!(msg = msg_create((const char*) payload)))
                          ^
1 warning generated.

This PR makes an attempt to fix them, not sure if it is the best way or other values/usage for parameters should be expected.

[Kaian]

Hi @miconda !!

I think those functions shouldn't have parameters, so I will change the usage rather than the declaration.

Thanks a lot for raising these warnings!

Best regards