xfce4-panel 4.21.x added include guards to libxfce4panel sub-headers,
requiring consumers to include <libxfce4panel/libxfce4panel.h> instead
of individual headers like <libxfce4panel/xfce-panel-plugin.h>.
Since there is no new upstream release with this fix, add
-DLIBXFCE4PANEL_COMPILATION to CFLAGS as a workaround to bypass the
include guard check.
Signed-off-by: Zhang Peng <peng.zhang1.cn@windriver.com>
Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>
f53ab756f2