vim: use empty PACKAGECONFIG for vim-native

* otherwise it depends on gtk+-native and we don't need gtkgui enabled
  in native builds as vim-native was introduced only for xxd-native in:

  commit 1dff2351aa
  Author: Martin Jansa <Martin.Jansa@gmail.com>
  Date:   Fri Mar 10 11:55:44 2017 +0100

    vim: add native BBCLASSEXTEND

    * some recipes might use xxd
    * with stricter host binaries available in PATH:
      http://lists.openembedded.org/pipermail/openembedded-core/2017-March/133886.html
      we cannot use xxd from host and it's not so common to add it into
      HOSTTOOL_NONFATAL
    * there is also smaller solution for xxd -i (which is what I need):
      https://github.com/gregkh/xxdi
      but after creating xxdi-native recipe for this I've discovered that
      perl on my host as well as perlnative doesn't provide File::Slurp
      used by this, so adding BBCLASSEXTEND here is easier solution

    Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-support/vim/vim_8.1.0347.bb

@@ -40,6 +40,7 @@ PACKAGECONFIG += " \
     ${@bb.utils.filter('DISTRO_FEATURES', 'acl selinux', d)} \
     ${@bb.utils.contains('DISTRO_FEATURES', 'x11', 'x11 gtkgui', '', d)} \
 "
+PACKAGECONFIG_class-native = ""
 
 PACKAGECONFIG[gtkgui] = "--enable-gui=gtk2,--enable-gui=no,gtk+,"
 PACKAGECONFIG[acl] = "--enable-acl,--disable-acl,acl,"