add plugin_common/include dirs to AC_OUTPUT
diff --git a/configure.in b/configure.in
index c3879b3..5eb5ba1 100644
--- a/configure.in
+++ b/configure.in
@@ -378,6 +378,8 @@
 	src/monkeys_audio_utilities/flac_ren/Makefile \
 	src/monkeys_audio_utilities/Makefile \
 	src/plugin_common/Makefile \
+	src/plugin_common/include/Makefile \
+	src/plugin_common/include/private/Makefile \
 	src/plugin_winamp2/Makefile \
 	src/plugin_winamp3/Makefile \
 	src/plugin_xmms/Makefile \