Removes leftovers from past tests for PCAP_NETMASK_UNKNOWN

Test first implemented in r33774 (80f18a2bc7),
finally removed in r37527 (f8004b792c)

configure

@@ -6380,7 +6380,6 @@ else
   # link with -lpcap for the purposes of this test
   LIBS_OLD="$LIBS"
   LIBS="$LIBS -lpcap"
-  PCAP_DEFINE_NETMASK_UNKNOWN
   for ac_func in pcap_set_immediate_mode
 do :
   ac_fn_c_check_func "$LINENO" "pcap_set_immediate_mode" "ac_cv_func_pcap_set_immediate_mode"

configure.ac

@@ -485,7 +485,6 @@ else
   # link with -lpcap for the purposes of this test
   LIBS_OLD="$LIBS"
   LIBS="$LIBS -lpcap"
-  PCAP_DEFINE_NETMASK_UNKNOWN
   AC_CHECK_FUNCS([pcap_set_immediate_mode])
   # Restore libs
   LIBS="$LIBS_OLD"

nsock/src/configure

@@ -3672,8 +3672,6 @@ $as_echo "#define HAVE_PCAP 1" >>confdefs.h
 fi
 
 
-PCAP_DEFINE_NETMASK_UNKNOWN
-
   ax_have_epoll_cppflags="${CPPFLAGS}"
   ac_fn_c_check_header_mongrel "$LINENO" "linux/version.h" "ac_cv_header_linux_version_h" "$ac_includes_default"
 if test "x$ac_cv_header_linux_version_h" = xyes; then :

nsock/src/configure.ac

@@ -180,8 +180,6 @@ if test "$have_libpcap" != "no"; then
 fi
 AC_SUBST(LIBPCAP_LIBS)
 
-PCAP_DEFINE_NETMASK_UNKNOWN
-
 AX_HAVE_EPOLL([AC_DEFINE(HAVE_EPOLL, 1, [epoll is available])], )
 AX_HAVE_POLL([AC_DEFINE(HAVE_POLL, 1, [poll is available])], )
 AC_CHECK_FUNCS(kqueue kevent, [AC_DEFINE(HAVE_KQUEUE)], )