meson: convert backends directory to Meson

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/configure b/configure
index a56de56..06a6e93 100755
--- a/configure
+++ b/configure
@@ -4741,6 +4741,7 @@
   if compile_prog "" "-lnuma" ; then
     numa=yes
     libs_softmmu="-lnuma $libs_softmmu"
+    numa_libs="-lnuma"
   else
     if test "$numa" = "yes" ; then
       feature_not_found "numa" "install numactl devel"
@@ -8367,6 +8368,7 @@
 
 if test "$numa" = "yes"; then
   echo "CONFIG_NUMA=y" >> $config_host_mak
+  echo "NUMA_LIBS=$numa_libs" >> $config_host_mak
 fi
 
 if test "$ccache_cpp2" = "yes"; then