acinclude: Drop DPDK_EXTRA_LIB variable.

AC_SEARCH_LIBS enables the libraries itself:

  checking for library containing get_mempolicy... -lnuma
  checking for library containing pcap_dump... -lpcap

So, they are available in LIBS. No need to add them twice.

Also, DPDK_EXTRA_LIB doesn't even work, because each check overwrites
the variable instead of appending the new library. It was first time
misused while making libnuma optional and copy-pasted to several places
after that.

Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>

acinclude.m4

@@ -242,7 +242,6 @@ AC_DEFUN([OVS_CHECK_DPDK], [
     esac
 
     DPDK_LIB="-ldpdk"
-    DPDK_EXTRA_LIB=""
 
     ovs_save_CFLAGS="$CFLAGS"
     ovs_save_LDFLAGS="$LDFLAGS"
@@ -261,7 +260,6 @@ AC_DEFUN([OVS_CHECK_DPDK], [
         ], [])
       ], [],
       [AC_SEARCH_LIBS([get_mempolicy],[numa],[],[AC_MSG_ERROR([unable to find libnuma, install the dependency package])])
-       DPDK_EXTRA_LIB="-lnuma"
        AC_DEFINE([VHOST_NUMA], [1], [NUMA Aware vHost support detected in DPDK.])])
 
     AC_COMPILE_IFELSE([
@@ -274,7 +272,6 @@ AC_DEFUN([OVS_CHECK_DPDK], [
         ], [])
       ], [],
       [AC_SEARCH_LIBS([pcap_dump],[pcap],[],[AC_MSG_ERROR([unable to find libpcap, install the dependency package])])
-       DPDK_EXTRA_LIB="-lpcap"
        AC_COMPILE_IFELSE([
          AC_LANG_PROGRAM(
            [
@@ -297,7 +294,6 @@ AC_DEFUN([OVS_CHECK_DPDK], [
         ], [])
       ], [],
       [AC_SEARCH_LIBS([mnl_attr_put],[mnl],[],[AC_MSG_ERROR([unable to find libmnl, install the dependency package])])
-       DPDK_EXTRA_LIB="-lmnl"
        AC_DEFINE([DPDK_MNL], [1], [MLX5 PMD detected in DPDK.])])
 
     # On some systems we have to add -ldl to link with dpdk
@@ -310,7 +306,7 @@ AC_DEFUN([OVS_CHECK_DPDK], [
     DPDKLIB_FOUND=false
     save_LIBS=$LIBS
     for extras in "" "-ldl"; do
-        LIBS="$DPDK_LIB $extras $save_LIBS $DPDK_EXTRA_LIB"
+        LIBS="$DPDK_LIB $extras $save_LIBS"
         AC_LINK_IFELSE(
            [AC_LANG_PROGRAM([#include <rte_config.h>
                              #include <rte_eal.h>],