Port SOCKET_LIBS to meson

Port the following snippet of autoconf to meson:

dnl Checks for socket stuff
VLC_SAVE_FLAGS
SOCKET_LIBS=""
AC_SEARCH_LIBS(connect, [socket], [
  AS_IF([test "$ac_cv_search_connect" != "none required"], [
    SOCKET_LIBS="$ac_cv_search_connect"
  ])
], [
  AS_IF([test "${SYS}" = "mingw32"], [
    SOCKET_LIBS="-lws2_32 -liphlpapi"
  ])
])