libtool: link: gcc -shared  -fPIC -DPIC  .libs/libxkb_la-xkb-plugin.o .libs/libxkb_la-xkb-keyboard.o .libs/libxkb_la-xkb-modifier.o .libs/libxkb_la-xkb-dialog.o .libs/libxkb_la-xkb-xfconf.o .libs/libxkb_la-xkb-cairo.o .libs/libxkb_la-xkb-util.o   -lxfce4panel-2.0 -lgmodule-2.0 -lxfce4ui-2 -lxfce4util -lxfconf-0 -ldbus-glib-1 -ldbus-1 -lxklavier -lwnck-3 -lgtk-3 -lgdk-3 -lpangocairo-1.0 -lpango-1.0 -latk-1.0 -lcairo-gobject -lgarcon-1 -lgthread-2.0 -lrsvg-2 -lm -lgio-2.0 -lgdk_pixbuf-2.0 -lgobject-2.0 -lglib-2.0 -lcairo  -pthread -pthread -pthread -pthread -pthread -pthread -g -O2 -fstack-protector-strong -Wl,-Bsymbolic-functions -Wl,-z -Wl,relro -Wl,-z -Wl,now -Wl,--as-needed -Wl,-O1 -Wl,-z -Wl,defs -Wl,--export-dynamic -pthread -pthread   -pthread -Wl,-soname -Wl,libxkb.so -o .libs/libxkb.so
.libs/libxkb_la-xkb-modifier.o: In function `xkb_modifier_handle_xevent':
./panel-plugin/xkb-modifier.c:165: undefined reference to `XOpenDisplay'
./panel-plugin/xkb-modifier.c:169: undefined reference to `XkbKeysymToModifiers'
./panel-plugin/xkb-modifier.c:171: undefined reference to `XCloseDisplay'
.libs/libxkb_la-xkb-modifier.o: In function `xkb_modifier_new':
./panel-plugin/xkb-modifier.c:100: undefined reference to `XOpenDisplay'
./panel-plugin/xkb-modifier.c:103: undefined reference to `XkbGetKeyboard'
./panel-plugin/xkb-modifier.c:110: undefined reference to `XGetAtomName'
./panel-plugin/xkb-modifier.c:113: undefined reference to `XkbGetIndicatorState'
./panel-plugin/xkb-modifier.c:124: undefined reference to `XkbFreeKeyboard'
./panel-plugin/xkb-modifier.c:127: undefined reference to `XkbQueryExtension'
./panel-plugin/xkb-modifier.c:128: undefined reference to `XCloseDisplay'
collect2: error: ld returned 1 exit status
Makefile:556: recipe for target 'libxkb.la' failed