nm: Split NM plugin and editor widget into separate libs

This will allow the plugin to load the editor widget matching the current
GTK version dynamically.

src/frontends/gnome/configure.ac

@@ -37,6 +37,9 @@ AC_PROG_GCC_TRADITIONAL
 AC_FUNC_MEMCMP
 AC_CHECK_FUNCS(select socket uname)
 
+AC_SEARCH_LIBS([dlopen], [dl dld], [], [ac_cv_search_dlopen=])
+AC_SUBST([DL_LIBS], "$ac_cv_search_dlopen")
+
 GETTEXT_PACKAGE=NetworkManager-strongswan
 AC_SUBST(GETTEXT_PACKAGE)
 AC_DEFINE_UNQUOTED(GETTEXT_PACKAGE,"$GETTEXT_PACKAGE", [Gettext package])